Annotation of html5/spec/scripting-1.html, revision 1.30
1.1 mike 1: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
2: <!DOCTYPE html>
3: <!-- when publishing, change bits marked ZZZ --><html lang="en-US-x-Hixie" class="split chapter"><head><title>4.3 Scripting — HTML5 </title><style type="text/css">
4: pre { margin-left: 2em; white-space: pre-wrap; }
5: h2 { margin: 3em 0 1em 0; }
6: h3 { margin: 2.5em 0 1em 0; }
7: h4 { margin: 2.5em 0 0.75em 0; }
8: h5, h6 { margin: 2.5em 0 1em; }
9: h1 + h2, h1 + h2 + h2 { margin: 0.75em 0 0.75em; }
10: h2 + h3, h3 + h4, h4 + h5, h5 + h6 { margin-top: 0.5em; }
11: p { margin: 1em 0; }
12: hr:not(.top) { display: block; background: none; border: none; padding: 0; margin: 2em 0; height: auto; }
13: dl, dd { margin-top: 0; margin-bottom: 0; }
14: dt { margin-top: 0.75em; margin-bottom: 0.25em; clear: left; }
15: dt + dt { margin-top: 0; }
16: dd dt { margin-top: 0.25em; margin-bottom: 0; }
17: dd p { margin-top: 0; }
18: dd dl + p { margin-top: 1em; }
19: dd table + p { margin-top: 1em; }
20: p + * > li, dd li { margin: 1em 0; }
21: dt, dfn { font-weight: bold; font-style: normal; }
22: dt dfn { font-style: italic; }
23: pre, code { font-size: inherit; font-family: monospace; font-variant: normal; }
24: pre strong { color: black; font: inherit; font-weight: bold; background: yellow; }
25: pre em { font-weight: bolder; font-style: normal; }
26: @media screen { code { color: orangered; } code :link, code :visited { color: inherit; } }
27: var sub { vertical-align: bottom; font-size: smaller; position: relative; top: 0.1em; }
28: table { border-collapse: collapse; border-style: hidden hidden none hidden; }
29: table thead, table tbody { border-bottom: solid; }
30: table tbody th:first-child { border-left: solid; }
31: table tbody th { text-align: left; }
32: table td, table th { border-left: solid; border-right: solid; border-bottom: solid thin; vertical-align: top; padding: 0.2em; }
33: blockquote { margin: 0 0 0 2em; border: 0; padding: 0; font-style: italic; }
34:
35: .bad, .bad *:not(.XXX) { color: gray; border-color: gray; background: transparent; }
36: .matrix, .matrix td { border: none; text-align: right; }
37: .matrix { margin-left: 2em; }
38: .dice-example { border-collapse: collapse; border-style: hidden solid solid hidden; border-width: thin; margin-left: 3em; }
39: .dice-example caption { width: 30em; font-size: smaller; font-style: italic; padding: 0.75em 0; text-align: left; }
40: .dice-example td, .dice-example th { border: solid thin; width: 1.35em; height: 1.05em; text-align: center; padding: 0; }
41:
42: .toc dfn, h1 dfn, h2 dfn, h3 dfn, h4 dfn, h5 dfn, h6 dfn { font: inherit; }
43: img.extra { float: right; }
44: pre.idl { border: solid thin; background: #EEEEEE; color: black; padding: 0.5em 1em; }
45: pre.idl :link, pre.idl :visited { color: inherit; background: transparent; }
46: pre.css { border: solid thin; background: #FFFFEE; color: black; padding: 0.5em 1em; }
47: pre.css:first-line { color: #AAAA50; }
48: dl.domintro { color: green; margin: 2em 0 2em 2em; padding: 0.5em 1em; border: none; background: #DDFFDD; }
49: hr + dl.domintro, div.impl + dl.domintro { margin-top: 2.5em; margin-bottom: 1.5em; }
50: dl.domintro dt, dl.domintro dt * { color: black; text-decoration: none; }
51: dl.domintro dd { margin: 0.5em 0 1em 2em; padding: 0; }
52: dl.domintro dd p { margin: 0.5em 0; }
53: dl.switch { padding-left: 2em; }
54: dl.switch > dt { text-indent: -1.5em; }
55: dl.switch > dt:before { content: '\21AA'; padding: 0 0.5em 0 0; display: inline-block; width: 1em; text-align: right; line-height: 0.5em; }
56: dl.triple { padding: 0 0 0 1em; }
57: dl.triple dt, dl.triple dd { margin: 0; display: inline }
58: dl.triple dt:after { content: ':'; }
59: dl.triple dd:after { content: '\A'; white-space: pre; }
60: .diff-old { text-decoration: line-through; color: silver; background: transparent; }
61: .diff-chg, .diff-new { text-decoration: underline; color: green; background: transparent; }
62: a .diff-new { border-bottom: 1px blue solid; }
63:
64: h2 { page-break-before: always; }
65: h1, h2, h3, h4, h5, h6 { page-break-after: avoid; }
66: h1 + h2, hr + h2.no-toc { page-break-before: auto; }
67:
1.29 mike 68: p > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]),
69: li > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]), { border-bottom: solid #9999CC; }
1.1 mike 70:
71: div.head { margin: 0 0 1em; padding: 1em 0 0 0; }
72: div.head p { margin: 0; }
73: div.head h1 { margin: 0; }
74: div.head .logo { float: right; margin: 0 1em; }
75: div.head .logo img { border: none } /* remove border from top image */
76: div.head dl { margin: 1em 0; }
77: div.head p.copyright, div.head p.alt { font-size: x-small; font-style: oblique; margin: 0; }
78:
79: body > .toc > li { margin-top: 1em; margin-bottom: 1em; }
80: body > .toc.brief > li { margin-top: 0.35em; margin-bottom: 0.35em; }
81: body > .toc > li > * { margin-bottom: 0.5em; }
82: body > .toc > li > * > li > * { margin-bottom: 0.25em; }
83: .toc, .toc li { list-style: none; }
84:
85: .brief { margin-top: 1em; margin-bottom: 1em; line-height: 1.1; }
86: .brief li { margin: 0; padding: 0; }
87: .brief li p { margin: 0; padding: 0; }
88:
89: .category-list { margin-top: -0.75em; margin-bottom: 1em; line-height: 1.5; }
90: .category-list::before { content: '\21D2\A0'; font-size: 1.2em; font-weight: 900; }
91: .category-list li { display: inline; }
92: .category-list li:not(:last-child)::after { content: ', '; }
93: .category-list li > span, .category-list li > a { text-transform: lowercase; }
94: .category-list li * { text-transform: none; } /* don't affect <code> nested in <a> */
95:
96: .XXX { color: #E50000; background: white; border: solid red; padding: 0.5em; margin: 1em 0; }
97: .XXX > :first-child { margin-top: 0; }
98: p .XXX { line-height: 3em; }
99: .annotation { border: solid thin black; background: #0C479D; color: white; position: relative; margin: 8px 0 20px 0; }
100: .annotation:before { position: absolute; left: 0; top: 0; width: 100%; height: 100%; margin: 6px -6px -6px 6px; background: #333333; z-index: -1; content: ''; }
101: .annotation :link, .annotation :visited { color: inherit; }
102: .annotation :link:hover, .annotation :visited:hover { background: transparent; }
103: .annotation span { border: none ! important; }
104: .note { color: green; background: transparent; font-family: sans-serif; }
105: .warning { color: red; background: transparent; }
106: .note, .warning { font-weight: bolder; font-style: italic; }
107: p.note, div.note { padding: 0.5em 2em; }
108: span.note { padding: 0 2em; }
109: .note p:first-child, .warning p:first-child { margin-top: 0; }
110: .note p:last-child, .warning p:last-child { margin-bottom: 0; }
111: .warning:before { font-style: normal; }
112: p.note:before { content: 'Note: '; }
113: p.warning:before { content: '\26A0 Warning! '; }
114:
115: .bookkeeping:before { display: block; content: 'Bookkeeping details'; font-weight: bolder; font-style: italic; }
116: .bookkeeping { font-size: 0.8em; margin: 2em 0; }
117: .bookkeeping p { margin: 0.5em 2em; display: list-item; list-style: square; }
1.9 mike 118: .bookkeeping dt { margin: 0.5em 2em 0; }
119: .bookkeeping dd { margin: 0 3em 0.5em; }
1.1 mike 120:
121: h4 { position: relative; z-index: 3; }
122: h4 + .element, h4 + div + .element { margin-top: -2.5em; padding-top: 2em; }
123: .element {
124: background: #EEEEFF;
125: color: black;
126: margin: 0 0 1em 0.15em;
127: padding: 0 1em 0.25em 0.75em;
128: border-left: solid #9999FF 0.25em;
129: position: relative;
130: z-index: 1;
131: }
132: .element:before {
133: position: absolute;
134: z-index: 2;
135: top: 0;
136: left: -1.15em;
137: height: 2em;
138: width: 0.9em;
139: background: #EEEEFF;
140: content: ' ';
141: border-style: none none solid solid;
142: border-color: #9999FF;
143: border-width: 0.25em;
144: }
145:
146: .example { display: block; color: #222222; background: #FCFCFC; border-left: double; margin-left: 2em; padding-left: 1em; }
147: td > .example:only-child { margin: 0 0 0 0.1em; }
148:
149: ul.domTree, ul.domTree ul { padding: 0 0 0 1em; margin: 0; }
150: ul.domTree li { padding: 0; margin: 0; list-style: none; position: relative; }
151: ul.domTree li li { list-style: none; }
152: ul.domTree li:first-child::before { position: absolute; top: 0; height: 0.6em; left: -0.75em; width: 0.5em; border-style: none none solid solid; content: ''; border-width: 0.1em; }
153: ul.domTree li:not(:last-child)::after { position: absolute; top: 0; bottom: -0.6em; left: -0.75em; width: 0.5em; border-style: none none solid solid; content: ''; border-width: 0.1em; }
154: ul.domTree span { font-style: italic; font-family: serif; }
155: ul.domTree .t1 code { color: purple; font-weight: bold; }
156: ul.domTree .t2 { font-style: normal; font-family: monospace; }
157: ul.domTree .t2 .name { color: black; font-weight: bold; }
158: ul.domTree .t2 .value { color: blue; font-weight: normal; }
159: ul.domTree .t3 code, .domTree .t4 code, .domTree .t5 code { color: gray; }
160: ul.domTree .t7 code, .domTree .t8 code { color: green; }
161: ul.domTree .t10 code { color: teal; }
162:
163: body.dfnEnabled dfn { cursor: pointer; }
164: .dfnPanel {
165: display: inline;
166: position: absolute;
167: z-index: 10;
168: height: auto;
169: width: auto;
170: padding: 0.5em 0.75em;
171: font: small sans-serif, Droid Sans Fallback;
172: background: #DDDDDD;
173: color: black;
174: border: outset 0.2em;
175: }
176: .dfnPanel * { margin: 0; padding: 0; font: inherit; text-indent: 0; }
177: .dfnPanel :link, .dfnPanel :visited { color: black; }
178: .dfnPanel p { font-weight: bolder; }
179: .dfnPanel * + p { margin-top: 0.25em; }
180: .dfnPanel li { list-style-position: inside; }
181:
182: #configUI { position: absolute; z-index: 20; top: 10em; right: 1em; width: 11em; font-size: small; }
183: #configUI p { margin: 0.5em 0; padding: 0.3em; background: #EEEEEE; color: black; border: inset thin; }
184: #configUI p label { display: block; }
185: #configUI #updateUI, #configUI .loginUI { text-align: center; }
186: #configUI input[type=button] { display: block; margin: auto; }
1.8 mike 187:
1.28 mike 188: fieldset { margin: 1em; }
189: fieldset > legend * + { margin-top: 0; }
190: fieldset > :last-child { margin-bottom: 0; }
191:
1.1 mike 192: </style><style type="text/css">
193:
194: .applies thead th > * { display: block; }
195: .applies thead code { display: block; }
196: .applies tbody th { whitespace: nowrap; }
197: .applies td { text-align: center; }
198: .applies .yes { background: yellow; }
199:
1.10 mike 200: .matrix, .matrix td { border: hidden; text-align: right; }
1.1 mike 201: .matrix { margin-left: 2em; }
202:
203: .dice-example { border-collapse: collapse; border-style: hidden solid solid hidden; border-width: thin; margin-left: 3em; }
204: .dice-example caption { width: 30em; font-size: smaller; font-style: italic; padding: 0.75em 0; text-align: left; }
205: .dice-example td, .dice-example th { border: solid thin; width: 1.35em; height: 1.05em; text-align: center; padding: 0; }
206:
1.17 mike 207: td.eg { border-width: thin; text-align: center; }
208:
1.1 mike 209: #table-example-1 { border: solid thin; border-collapse: collapse; margin-left: 3em; }
210: #table-example-1 * { font-family: "Essays1743", serif; line-height: 1.01em; }
211: #table-example-1 caption { padding-bottom: 0.5em; }
212: #table-example-1 thead, #table-example-1 tbody { border: none; }
213: #table-example-1 th, #table-example-1 td { border: solid thin; }
214: #table-example-1 th { font-weight: normal; }
215: #table-example-1 td { border-style: none solid; vertical-align: top; }
216: #table-example-1 th { padding: 0.5em; vertical-align: middle; text-align: center; }
217: #table-example-1 tbody tr:first-child td { padding-top: 0.5em; }
218: #table-example-1 tbody tr:last-child td { padding-bottom: 1.5em; }
219: #table-example-1 tbody td:first-child { padding-left: 2.5em; padding-right: 0; width: 9em; }
220: #table-example-1 tbody td:first-child::after { content: leader(". "); }
221: #table-example-1 tbody td { padding-left: 2em; padding-right: 2em; }
222: #table-example-1 tbody td:first-child + td { width: 10em; }
223: #table-example-1 tbody td:first-child + td ~ td { width: 2.5em; }
224: #table-example-1 tbody td:first-child + td + td + td ~ td { width: 1.25em; }
225:
226: .apple-table-examples { border: none; border-collapse: separate; border-spacing: 1.5em 0em; width: 40em; margin-left: 3em; }
227: .apple-table-examples * { font-family: "Times", serif; }
228: .apple-table-examples td, .apple-table-examples th { border: none; white-space: nowrap; padding-top: 0; padding-bottom: 0; }
229: .apple-table-examples tbody th:first-child { border-left: none; width: 100%; }
230: .apple-table-examples thead th:first-child ~ th { font-size: smaller; font-weight: bolder; border-bottom: solid 2px; text-align: center; }
231: .apple-table-examples tbody th::after, .apple-table-examples tfoot th::after { content: leader(". ") }
232: .apple-table-examples tbody th, .apple-table-examples tfoot th { font: inherit; text-align: left; }
233: .apple-table-examples td { text-align: right; vertical-align: top; }
234: .apple-table-examples.e1 tbody tr:last-child td { border-bottom: solid 1px; }
235: .apple-table-examples.e1 tbody + tbody tr:last-child td { border-bottom: double 3px; }
236: .apple-table-examples.e2 th[scope=row] { padding-left: 1em; }
237: .apple-table-examples sup { line-height: 0; }
238:
239: .details-example img { vertical-align: top; }
240:
241: #named-character-references-table {
1.24 mike 242: white-space: nowrap;
1.1 mike 243: font-size: 0.6em;
1.24 mike 244: column-width: 30em;
1.1 mike 245: column-gap: 1em;
1.24 mike 246: -moz-column-width: 30em;
1.1 mike 247: -moz-column-gap: 1em;
1.24 mike 248: -webkit-column-width: 30em;
1.1 mike 249: -webkit-column-gap: 1em;
250: }
1.24 mike 251: #named-character-references-table > table > tbody > tr > td:first-child + td,
1.1 mike 252: #named-character-references-table > table > tbody > tr > td:last-child { text-align: center; }
253: #named-character-references-table > table > tbody > tr > td:last-child:hover > span { position: absolute; top: auto; left: auto; margin-left: 0.5em; line-height: 1.2; font-size: 5em; border: outset; padding: 0.25em 0.5em; background: white; width: 1.25em; height: auto; text-align: center; }
1.24 mike 254: #named-character-references-table > table > tbody > tr#entity-CounterClockwiseContourIntegral > td:first-child { font-size: 0.5em; }
1.1 mike 255:
1.2 mike 256: .glyph.control { color: red; }
257:
1.4 mike 258: @font-face {
259: font-family: 'Essays1743';
260: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743.ttf');
261: }
262: @font-face {
263: font-family: 'Essays1743';
264: font-weight: bold;
265: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-Bold.ttf');
266: }
267: @font-face {
268: font-family: 'Essays1743';
269: font-style: italic;
270: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-Italic.ttf');
271: }
272: @font-face {
273: font-family: 'Essays1743';
274: font-style: italic;
275: font-weight: bold;
276: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-BoldItalic.ttf');
277: }
278:
1.1 mike 279: </style><style type="text/css">
280: .domintro:before { display: table; margin: -1em -0.5em -0.5em auto; width: auto; content: 'This box is non-normative. Implementation requirements are given below this box.'; color: black; font-style: italic; border: solid 2px; background: white; padding: 0 0.25em; }
281: </style><link href="data:text/css," id="complete" rel="stylesheet" title="Complete specification"><link href="data:text/css,.impl%20%7B%20display:%20none;%20%7D%0Ahtml%20%7B%20border:%20solid%20yellow;%20%7D%20.domintro:before%20%7B%20display:%20none;%20%7D" id="author" rel="alternate stylesheet" title="Author documentation only"><link href="data:text/css,.impl%20%7B%20background:%20%23FFEEEE;%20%7D%20.domintro:before%20%7B%20background:%20%23FFEEEE;%20%7D" id="highlight" rel="alternate stylesheet" title="Highlight implementation requirements"><script type="text/javascript">
282: function getCookie(name) {
283: var params = location.search.substr(1).split("&");
284: for (var index = 0; index < params.length; index++) {
285: if (params[index] == name)
286: return "1";
287: var data = params[index].split("=");
288: if (data[0] == name)
289: return unescape(data[1]);
290: }
291: var cookies = document.cookie.split("; ");
292: for (var index = 0; index < cookies.length; index++) {
293: var data = cookies[index].split("=");
294: if (data[0] == name)
295: return unescape(data[1]);
296: }
297: return null;
298: }
299: function load(script) {
300: var e = document.createElement('script');
1.30 ! mike 301: e.setAttribute('src', 'http://www.whatwg.org/specs/web-apps/current-work/' + script + '?' + encodeURIComponent(location) + '&' + encodeURIComponent(document.referrer));
1.1 mike 302: document.body.appendChild(e);
303: }
304: function init() {
305: if (location.search == '?slow-browser')
306: return;
307: var configUI = document.createElement('div');
308: configUI.id = 'configUI';
309: document.body.appendChild(configUI);
310: // load('reviewer.js'); // would need cross-site XHR
311: if (document.getElementById('head'))
312: load('toc.js');
313: load('styler.js');
314: // load('updater.js'); // would need cross-site XHR
315: load('dfn.js'); // doesn't support split-out specs, but, oh well.
316: // load('status.js'); // would need cross-site XHR
317: if (getCookie('profile') == '1')
318: document.getElementsByTagName('h2')[0].textContent += '; load: ' + (new Date() - loadTimer) + 'ms';
319: fixBrokenLink();
320: }
1.30 ! mike 321: </script><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css">
1.1 mike 322: <script src="link-fixup.js"></script>
323: <link href="semantics.html" title="4 The elements of HTML" rel="prev">
324: <link href="spec.html#contents" title="Table of contents" rel="index">
325: <link href="sections.html" title="4.4 Sections" rel="next">
326: </head><body onload="fixBrokenLink(); init()"><div class="head" id="head">
327: <p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>
1.3 mike 328:
1.1 mike 329: <h1>HTML5</h1>
330: </div><div>
331: <a href="semantics.html">← 4 The elements of HTML</a> –
332: <a href="spec.html#contents">Table of contents</a> –
333: <a href="sections.html">4.4 Sections →</a>
334: <ol class="toc"><li><ol><li><a href="scripting-1.html#scripting-1"><span class="secno">4.3 </span>Scripting</a>
335: <ol><li><a href="scripting-1.html#script"><span class="secno">4.3.1 </span>The <code>script</code> element</a>
336: <ol><li><a href="scripting-1.html#scriptingLanguages"><span class="secno">4.3.1.1 </span>Scripting languages</a></li><li><a href="scripting-1.html#restrictions-for-contents-of-script-elements"><span class="secno">4.3.1.2 </span>Restrictions for contents of <code>script</code> elements</a></li><li><a href="scripting-1.html#inline-documentation-for-external-scripts"><span class="secno">4.3.1.3 </span>Inline documentation for external scripts</a></li></ol></li><li><a href="scripting-1.html#the-noscript-element"><span class="secno">4.3.2 </span>The <code>noscript</code> element</a></li></ol></li></ol></li></ol></div>
337:
1.15 mike 338: <h3 id="scripting-1"><span class="secno">4.3 </span>Scripting</h3><p>Scripts allow authors to add interactivity to their documents.</p><p>Authors are encouraged to use declarative alternatives to
1.1 mike 339: scripting where possible, as declarative mechanisms are often more
340: maintainable, and many users disable scripting.</p><div class="example">
341: <p>For example, instead of using script to show or hide a section
342: to show more details, the <code><a href="interactive-elements.html#the-details-element">details</a></code> element could be
343: used.</p>
344: </div><p>Authors are also encouraged to make their applications degrade
345: gracefully in the absence of scripting support.</p><div class="example">
346: <p>For example, if an author provides a link in a table header to
347: dynamically resort the table, the link could also be made to
348: function without scripts by requesting the sorted table from the
349: server.</p>
1.15 mike 350: </div><h4 id="script"><span class="secno">4.3.1 </span>The <dfn><code>script</code></dfn> element</h4><dl class="element"><dt>Categories</dt>
1.1 mike 351: <dd><a href="content-models.html#metadata-content">Metadata content</a>.</dd>
352: <dd><a href="content-models.html#flow-content">Flow content</a>.</dd>
353: <dd><a href="content-models.html#phrasing-content">Phrasing content</a>.</dd>
1.16 mike 354: <dt>Contexts in which this element can be used:</dt>
1.1 mike 355: <dd>Where <a href="content-models.html#metadata-content">metadata content</a> is expected.</dd>
356: <dd>Where <a href="content-models.html#phrasing-content">phrasing content</a> is expected.</dd>
357: <dt>Content model:</dt>
358: <dd>If there is no <code title="attr-script-src"><a href="#attr-script-src">src</a></code>
359: attribute, depends on the value of the <code title="attr-script-type"><a href="#attr-script-type">type</a></code> attribute, but must match
360: <a href="#restrictions-for-contents-of-script-elements">script content restrictions</a>.</dd>
361: <dd>If there <em>is</em> a <code title="attr-script-src"><a href="#attr-script-src">src</a></code>
362: attribute, the element must be either empty or contain only
363: <a href="#inline-documentation-for-external-scripts">script documentation</a> that also matches <a href="#restrictions-for-contents-of-script-elements">script
364: content restrictions</a>.</dd>
365: <dt>Content attributes:</dt>
366: <dd><a href="elements.html#global-attributes">Global attributes</a></dd>
367: <dd><code title="attr-script-src"><a href="#attr-script-src">src</a></code></dd>
368: <dd><code title="attr-script-async"><a href="#attr-script-async">async</a></code></dd>
369: <dd><code title="attr-script-defer"><a href="#attr-script-defer">defer</a></code></dd>
370: <dd><code title="attr-script-type"><a href="#attr-script-type">type</a></code></dd>
371: <dd><code title="attr-script-charset"><a href="#attr-script-charset">charset</a></code></dd>
372: <dt>DOM interface:</dt>
373: <dd>
374: <pre class="idl">interface <dfn id="htmlscriptelement">HTMLScriptElement</dfn> : <a href="elements.html#htmlelement">HTMLElement</a> {
375: attribute DOMString <a href="#dom-script-src" title="dom-script-src">src</a>;
376: attribute boolean <a href="#dom-script-async" title="dom-script-async">async</a>;
377: attribute boolean <a href="#dom-script-defer" title="dom-script-defer">defer</a>;
378: attribute DOMString <a href="#dom-script-type" title="dom-script-type">type</a>;
379: attribute DOMString <a href="#dom-script-charset" title="dom-script-charset">charset</a>;
380: attribute DOMString <a href="#dom-script-text" title="dom-script-text">text</a>;
381: };</pre>
382: </dd>
383: </dl><p>The <code><a href="#script">script</a></code> element allows authors to include dynamic
384: script and data blocks in their documents. The element does not
385: <a href="rendering.html#represents" title="represents">represent</a> content for the user.</p><p>When used to include dynamic scripts, the scripts may either be
386: embedded inline or may be imported from an external file using the
387: <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute. If the language
388: is not that described by "<code title="">text/javascript</code>",
389: then the <code title="attr-script-type"><a href="#attr-script-type">type</a></code> attribute must
390: be present, as described below.</p><p>When used to include data blocks (as opposed to scripts), the
391: data must be embedded inline, the format of the data must be given
392: using the <code title="attr-script-type"><a href="#attr-script-type">type</a></code> attribute, and
393: the <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute must not be
394: specified.</p><p>The <dfn id="attr-script-type" title="attr-script-type"><code>type</code></dfn>
395: attribute gives the language of the script or format of the data. If
396: the attribute is present, its value must be a <a href="infrastructure.html#valid-mime-type">valid MIME
397: type</a>. The <code title="">charset</code> parameter must not be
398: specified. The default, which is used if the attribute is absent,
399: is "<code title="">text/javascript</code>".</p><p>The <dfn id="attr-script-src" title="attr-script-src"><code>src</code></dfn>
400: attribute, if specified, gives the address of the external script
401: resource to use. The value of the attribute must be a <a href="urls.html#valid-non-empty-url-potentially-surrounded-by-spaces">valid
402: non-empty URL potentially surrounded by spaces</a> identifying a
403: script resource of the type given by the <code title="attr-script-type"><a href="#attr-script-type">type</a></code> attribute, if the attribute is
404: present, or of the type "<code title="">text/javascript</code>", if
405: the attribute is absent. A resource is a script resource of a given
406: type if that type identifies a scripting language and the resource
407: conforms with the requirements of that language's specification.</p><p>The <dfn id="attr-script-charset" title="attr-script-charset"><code>charset</code></dfn>
408: attribute gives the character encoding of the external script
409: resource. The attribute must not be specified if the <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute is not present. If the
410: attribute is set, its value must be a valid character encoding name,
411: must be an <a href="infrastructure.html#ascii-case-insensitive">ASCII case-insensitive</a> match for the
412: <a href="infrastructure.html#preferred-mime-name">preferred MIME name</a> for that encoding, and must match
413: the encoding given in the <code title="">charset</code> parameter of
414: the <a href="fetching-resources.html#content-type" title="Content-Type">Content-Type metadata</a> of the
415: external file, if any. <a href="references.html#refsIANACHARSET">[IANACHARSET]</a></p><p>The <dfn id="attr-script-async" title="attr-script-async"><code>async</code></dfn> and
416: <dfn id="attr-script-defer" title="attr-script-defer"><code>defer</code></dfn> attributes
417: are <a href="common-microsyntaxes.html#boolean-attribute" title="boolean attribute">boolean attributes</a> that
418: indicate how the script should be executed. The <code title="attr-script-defer"><a href="#attr-script-defer">defer</a></code> and <code title="attr-script-async"><a href="#attr-script-async">async</a></code> attributes must not be
419: specified if the <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute
420: is not present.</p><p>There are three possible modes that can be selected using these
421: attributes. If the <code title="attr-script-async"><a href="#attr-script-async">async</a></code>
422: attribute is present, then the script will be executed
423: asynchronously, as soon as it is available. If the <code title="attr-script-async"><a href="#attr-script-async">async</a></code> attribute is not present but
424: the <code title="attr-script-defer"><a href="#attr-script-defer">defer</a></code> attribute is
425: present, then the script is executed when the page has finished
426: parsing. If neither attribute is present, then the script is
427: fetched and executed immediately, before the user agent continues
428: parsing the page.</p><p class="note">The exact processing details for these attributes
429: are, for mostly historical reasons, somewhat non-trivial, involving
430: a number of aspects of HTML. The implementation requirements are
431: therefore by necessity scattered throughout the specification. The
432: algorithms below (in this section) describe the core of this
433: processing, but these algorithms reference and are referenced by the
434: parsing rules for <code><a href="#script">script</a></code> <a href="tokenization.html#scriptTag">start</a>
435: and <a href="tokenization.html#scriptEndTag">end</a> tags in HTML, <a href="tokenization.html#scriptForeignEndTag">in foreign content</a>, and <a href="the-xhtml-syntax.html#scriptTagXML">in XML</a>, the rules for the <code title="dom-document-write"><a href="apis-in-html-documents.html#dom-document-write">document.write()</a></code> method, the
436: handling of <a href="webappapis.html#scripting">scripting</a>, etc.</p><p>The <code title="attr-script-defer"><a href="#attr-script-defer">defer</a></code> attribute may be
437: specified even if the <code title="attr-script-async"><a href="#attr-script-async">async</a></code>
438: attribute is specified, to cause legacy Web browsers that only
439: support <code title="attr-script-defer"><a href="#attr-script-defer">defer</a></code> (and not <code title="attr-script-async"><a href="#attr-script-async">async</a></code>) to fall back to the <code title="attr-script-defer"><a href="#attr-script-defer">defer</a></code> behavior instead of the
440: synchronous blocking behavior that is the default.</p><p>Changing the <code title="attr-script-src"><a href="#attr-script-src">src</a></code>, <code title="attr-script-type"><a href="#attr-script-type">type</a></code>, <code title="attr-script-charset"><a href="#attr-script-charset">charset</a></code>, <code title="attr-script-async"><a href="#attr-script-async">async</a></code>, and <code title="attr-script-defer"><a href="#attr-script-defer">defer</a></code> attributes dynamically has no
441: direct effect; these attribute are only used at specific times
442: described below.</p><!-- by implication, changes to the base URL
443: also have no effect --><div class="impl">
444:
445: <p>A <code><a href="#script">script</a></code> element has several associated pieces of
446: state.</p>
447:
448: <p>The first is a flag indicating whether or not the script block
449: has been <dfn id="already-started">"already started"</dfn>. Initially,
450: <code><a href="#script">script</a></code> elements must have this flag unset (script
451: blocks, when created, are not "already started"). When a
452: <code><a href="#script">script</a></code> element is cloned, the "already started" flag,
453: if set, must be propagated to the clone when it is created.</p>
454:
455: <p>The second is a flag indicating whether the element was
456: <dfn id="parser-inserted">"parser-inserted"</dfn>. Initially, <code><a href="#script">script</a></code>
457: elements must have this flag unset. It is set by the <a href="parsing.html#html-parser">HTML
458: parser</a> and the <a href="the-xhtml-syntax.html#xml-parser">XML parser</a> on <code><a href="#script">script</a></code>
459: elements they insert and affects the processing of those
460: elements.</p>
461:
462: <p>The third is a flag indicating whether or not the script block is
463: <dfn id="ready-to-be-parser-executed">"ready to be parser-executed"</dfn>. Initially,
464: <code><a href="#script">script</a></code> elements must have this flag unset (script
465: blocks, when created, are not "ready to be parser-executed"). This
466: flag is used only for elements that are also
467: <a href="#parser-inserted">"parser-inserted"</a>, to let the parser know when to
468: execute the script.</p>
469:
1.23 mike 470: <p>The last few pieces of state are <dfn id="the-script-block-s-type"><var>the script block's
471: type</var></dfn>, <dfn id="the-script-block-s-character-encoding"><var>the script block's character
472: encoding</var></dfn>, and <dfn id="the-script-block-s-fallback-character-encoding"><var>the script block's fallback
473: character encoding</var></dfn>. They are determined when the script
474: is run, based on the attributes on the element at that time, and the
475: <code><a href="infrastructure.html#document">Document</a></code> of the <code><a href="#script">script</a></code> element.</p>
1.1 mike 476:
1.16 mike 477: <p>When a <code><a href="#script">script</a></code> element that is not marked as being
1.1 mike 478: <a href="#parser-inserted">"parser-inserted"</a> experiences one of the events listed
479: in the following list, the user agent must synchronously <a href="#running-a-script" title="running a script">run</a> the <code><a href="#script">script</a></code>
480: element:</p>
481:
482: <ul><li>The <code><a href="#script">script</a></code> element gets <a href="infrastructure.html#insert-an-element-into-a-document" title="insert an
483: element into a document">inserted into a document</a>.</li>
484:
485: <li>The <code><a href="#script">script</a></code> element is <a href="infrastructure.html#in-a-document">in a
486: <code>Document</code></a> and its child nodes are changed.</li>
487:
488: <li>The <code><a href="#script">script</a></code> element is <a href="infrastructure.html#in-a-document">in a
489: <code>Document</code></a> and has a <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute set where previously
490: the element had no such attribute.</li>
491:
492: </ul><p><dfn id="running-a-script" title="running a script">Running a script</dfn>: When a
493: <code><a href="#script">script</a></code> element is to be run, the user agent must act as
494: follows:</p>
495:
1.19 mike 496: <ol><li>
1.16 mike 497:
1.19 mike 498: <p>If the <code><a href="#script">script</a></code> element is marked as having
499: <a href="#already-started">"already started"</a>, then the user agent must abort
500: these steps at this point. The script is not executed.</p>
1.16 mike 501:
502: </li>
503:
1.18 mike 504: <li>
505:
506: <p>If the element has its <a href="#parser-inserted">"parser-inserted"</a> flag set,
507: then set <var title="">was-parser-inserted</var> to true and unset
508: the element's <a href="#parser-inserted">"parser-inserted"</a> flag. Otherwise, set
509: <var title="">was-parser-inserted</var> to false.</p>
510:
511: <p class="note">This is done so that if parser-inserted
512: <code><a href="#script">script</a></code> elements fail to run when the parser tries to
513: run them, e.g. because they are empty or specify an unsupported
514: scripting language, another script can later mutate them and cause
515: them to run again.</p>
516:
517: <!-- q.v. http://hsivonen.iki.fi/test/moz/script-setting-src-on-parser-inserted-script.html -->
518:
519: </li>
520:
1.16 mike 521: <li id="script-processing-empty">
522:
523: <p>If the element has no <code title="attr-script-src"><a href="#attr-script-src">src</a></code>
1.18 mike 524: attribute, and its child nodes, if any, consist only of comment
525: nodes and empty <a href="infrastructure.html#text-node" title="text node">text nodes</a>, then
526: the user agent must abort these steps at this point. The script is
527: not executed.</p>
1.16 mike 528:
529: </li>
530:
1.25 mike 531: <li>
532:
533: <p>If the element is not <a href="infrastructure.html#in-a-document">in a <code>Document</code></a>,
534: then the user agent must abort these steps at this point. The
535: script is not executed.</p>
536:
537: </li>
538:
1.16 mike 539: <li id="script-processing-prepare">
1.1 mike 540:
541: <p>If either:</p>
542:
543: <ul class="brief"><li>the <code><a href="#script">script</a></code> element has a <code title="attr-script-type"><a href="#attr-script-type">type</a></code> attribute and its value is
544: the empty string, or</li>
545:
546: <li>the <code><a href="#script">script</a></code> element has no <code title="attr-script-type"><a href="#attr-script-type">type</a></code> attribute but it has a <code title="attr-script-language"><a href="obsolete.html#attr-script-language">language</a></code> attribute and
547: <em>that</em> attribute's value is the empty string, or</li>
548:
549: <li>the <code><a href="#script">script</a></code> element has neither a <code title="attr-script-type"><a href="#attr-script-type">type</a></code> attribute nor a <code title="attr-script-language"><a href="obsolete.html#attr-script-language">language</a></code> attribute, then</li>
550:
551: </ul><p>...let <var><a href="#the-script-block-s-type">the script block's type</a></var> for this
552: <code><a href="#script">script</a></code> element be "<code title="">text/javascript</code>".</p>
553:
554: <p>Otherwise, if the <code><a href="#script">script</a></code> element has a <code title="attr-script-type"><a href="#attr-script-type">type</a></code> attribute, let <var><a href="#the-script-block-s-type">the
555: script block's type</a></var> for this <code><a href="#script">script</a></code> element be
556: the value of that attribute with any leading or trailing sequences
557: of <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>
558: removed.</p>
559:
560: <p>Otherwise, the element has a non-empty <code title="attr-script-language"><a href="obsolete.html#attr-script-language">language</a></code> attribute; let
561: <var><a href="#the-script-block-s-type">the script block's type</a></var> for this <code><a href="#script">script</a></code>
562: element be the concatenation of the string "<code title="">text/</code>" followed by the value of the <code title="attr-script-language"><a href="obsolete.html#attr-script-language">language</a></code> attribute.</p> <!--
563: user agents already support, e.g., type="text/javascript1.3", so
564: we don't have to support that separately. -->
565:
566: <p class="note">The <code title="attr-script-language"><a href="obsolete.html#attr-script-language">language</a></code> attribute is never
567: conforming, and is always ignored if there is a <code title="attr-script-type"><a href="#attr-script-type">type</a></code> attribute present.</p>
568:
569: </li>
570:
1.16 mike 571: <li>
572:
573: <p>If the user agent does not <a href="#support-the-scripting-language">support the scripting
574: language</a> given by <var><a href="#the-script-block-s-type">the script block's type</a></var> for
575: this <code><a href="#script">script</a></code> element, then the user agent must abort
576: these steps at this point. The script is not executed.</p>
577:
578: </li>
579:
1.18 mike 580: <li id="script-processing-start">
581:
582: <p>The user agent must set the element's <a href="#already-started">"already
583: started"</a> flag.</p>
584:
585: </li>
586:
587: <li>
588:
589: <p>If <var title="">was-parser-inserted</var> is true, then flag
590: the element as <a href="#parser-inserted">"parser-inserted"</a> again.</p>
591:
592: </li>
593:
1.19 mike 594: <li id="script-processing-noscript">
595:
596: <p>If <a href="webappapis.html#concept-n-noscript" title="concept-n-noscript">scripting is
597: disabled</a> for the <code><a href="#script">script</a></code> element, then the user
598: agent must abort these steps at this point. The script is not
599: executed.</p>
600:
601: </li>
602:
1.1 mike 603: <li id="script-processing-for">
604:
605: <p>If the <code><a href="#script">script</a></code> element has an <code title="attr-script-event"><a href="obsolete.html#attr-script-event">event</a></code> attribute and a <code title="attr-script-for"><a href="obsolete.html#attr-script-for">for</a></code> attribute, then run these
606: substeps:</p>
607:
608: <ol><li><p>Let <var title="">for</var> be the value of the <code title="attr-script-for"><a href="obsolete.html#attr-script-for">for</a></code> attribute.</p></li>
609:
610: <li><p>Let <var title="">event</var> be the value of the <code title="attr-script-event"><a href="obsolete.html#attr-script-event">event</a></code> attribute.</p></li>
611:
612: <li><p><a href="common-microsyntaxes.html#strip-leading-and-trailing-whitespace">Strip leading and trailing whitespace</a> from
613: <var title="">event</var> and <var title="">for</var>.</p></li>
614:
615: <li><p>If <var title="">for</var> is not an <a href="infrastructure.html#ascii-case-insensitive">ASCII
616: case-insensitive</a> match for the string "<code title="">window</code>", then the user agent must abort these
617: steps at this point. The script is not executed.</p></li>
618:
619: <li><p>If <var title="">event</var> is not an <a href="infrastructure.html#ascii-case-insensitive">ASCII
620: case-insensitive</a> match for either the string "<code title="">onload</code>" or the string "<code title="">onload()</code>", then the user agent must abort these
621: steps at this point. The script is not executed.</p></li>
622:
623: </ol></li>
624:
1.19 mike 625: <li id="script-processing-encoding">
626:
627: <p>If the <code><a href="#script">script</a></code> element has a <code title="attr-script-charset"><a href="#attr-script-charset">charset</a></code> attribute, then let
628: <var><a href="#the-script-block-s-character-encoding">the script block's character encoding</a></var> for this
629: <code><a href="#script">script</a></code> element be the encoding given by the <code title="attr-script-charset"><a href="#attr-script-charset">charset</a></code> attribute.</p>
630:
1.23 mike 631: <p>Otherwise, let <var><a href="#the-script-block-s-fallback-character-encoding">the script block's fallback character
632: encoding</a></var> for this <code><a href="#script">script</a></code> element be the same as
633: <a href="dom.html#document-s-character-encoding" title="document's character encoding">the encoding of the
634: document itself</a>.</p>
635:
636: <p class="note">Only one of these two pieces of state is set.</p>
1.19 mike 637:
638: </li>
639:
1.1 mike 640: <li id="script-processing-src-prepare">
641:
642: <p>If the element has a <code title="attr-script-src"><a href="#attr-script-src">src</a></code>
643: attribute whose value is not the empty string, then the value of
644: that attribute must be <a href="urls.html#resolve-a-url" title="resolve a url">resolved</a>
645: relative to the element, and if that is successful, the specified
646: resource must then be <a href="fetching-resources.html#fetch" title="fetch">fetched</a>, from the
647: <a href="origin-0.html#origin">origin</a> of the element's <code><a href="infrastructure.html#document">Document</a></code>.</p>
648: <!-- not http-origin privacy sensitive -->
649:
650: <p>If the <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute's
651: value is the empty string or if it could not be resolved, then the
652: user agent must <a href="webappapis.html#queue-a-task">queue a task</a> to <a href="webappapis.html#fire-a-simple-event">fire a simple
653: event</a> named <code title="event-error">error</code> at the
654: element, and abort these steps.</p>
655:
656: <p>For historical reasons, if the <a href="urls.html#url">URL</a> is a <a href="webappapis.html#javascript-protocol" title="javascript protocol"><code title="">javascript:</code>
657: URL</a>, then the user agent must not, despite the requirements
658: in the definition of the <a href="fetching-resources.html#fetch" title="fetch">fetching</a>
659: algorithm, actually execute the script in the URL; instead the
660: user agent must act as if it had received an empty HTTP 400
661: response.</p>
662:
663: <p>For performance reasons, user agents may start fetching the
664: script as soon as the attribute is set, instead, in the hope that
665: the element will be inserted into the document. Either way, once
666: the element is <a href="infrastructure.html#insert-an-element-into-a-document" title="insert an element into a
667: document">inserted into the document</a>, the load must have
668: started. If the UA performs such prefetching, but the element is
669: never inserted in the document, or the <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute is dynamically
670: changed,<!-- or the base URL is dynamically changed,--> then the
671: user agent will not execute the script, and the fetching process
672: will have been effectively wasted.</p>
673:
674: </li>
675:
676: <li>
677:
678: <p>Then, the first of the following options that describes the
679: situation must be followed:</p>
680:
681: <dl class="switch"><dt id="script-processing-defer">If the element has a <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute, and the element has
682: a <code title="attr-script-defer"><a href="#attr-script-defer">defer</a></code> attribute, and the
683: element has been flagged as <a href="#parser-inserted">"parser-inserted"</a>, and
684: the element does not have an <code title="attr-script-async"><a href="#attr-script-async">async</a></code> attribute</dt>
685:
686: <dd>
687:
688: <p>The element must be added to the end of the <dfn id="list-of-scripts-that-will-execute-when-the-document-has-finished-parsing">list of
689: scripts that will execute when the document has finished
1.20 mike 690: parsing</dfn> associated with the <code><a href="infrastructure.html#document">Document</a></code> of the
691: parser that created the element.</p>
1.1 mike 692:
693: <p>The <a href="webappapis.html#concept-task" title="concept-task">task</a> that the
694: <a href="webappapis.html#networking-task-source">networking task source</a> places on the <a href="webappapis.html#task-queue">task
695: queue</a> once the <a href="fetching-resources.html#fetch" title="fetch">fetching
696: algorithm</a> has completed must set the element's
697: <a href="#ready-to-be-parser-executed">"ready to be parser-executed"</a> flag. The parser will
698: handle executing the script.</p>
699:
700: </dd>
701:
702:
703: <dt id="script-processing-parser-inserted">If the element has a
704: <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute, and the
705: element has been flagged as <a href="#parser-inserted">"parser-inserted"</a>, and
706: the element does not have an <code title="attr-script-async"><a href="#attr-script-async">async</a></code> attribute</dt>
707:
708: <dd>
709:
710: <p>The element is the <a href="#pending-parsing-blocking-script">pending parsing-blocking
1.20 mike 711: script</a> of the <code><a href="infrastructure.html#document">Document</a></code> of the parser that
712: created the element. (There can only be one such script per
713: <code><a href="infrastructure.html#document">Document</a></code> at a time.)</p>
1.1 mike 714:
715: <p>The <a href="webappapis.html#concept-task" title="concept-task">task</a> that the
716: <a href="webappapis.html#networking-task-source">networking task source</a> places on the <a href="webappapis.html#task-queue">task
717: queue</a> once the <a href="fetching-resources.html#fetch" title="fetch">fetching
718: algorithm</a> has completed must set the element's
719: <a href="#ready-to-be-parser-executed">"ready to be parser-executed"</a> flag. The parser will
720: handle executing the script.</p>
721:
722: </dd>
723:
724:
725: <dt id="script-processing-style-delayed">If the element does not
726: have a <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute, but
1.21 mike 727: there is <a href="semantics.html#a-style-sheet-that-is-blocking-scripts">a style sheet that is blocking scripts</a>, and
728: the element has been flagged as
729: <a href="#parser-inserted">"parser-inserted"</a></dt>
1.1 mike 730:
731: <dd>
732:
733: <p>The element is the <a href="#pending-parsing-blocking-script">pending parsing-blocking
1.20 mike 734: script</a> of the <code><a href="infrastructure.html#document">Document</a></code> of the parser that
735: created the element. (There can only be one such script per
736: <code><a href="infrastructure.html#document">Document</a></code> at a time.)</p>
1.1 mike 737:
738: <p>Set the element's <a href="#ready-to-be-parser-executed">"ready to be parser-executed"</a>
739: flag. The parser will handle executing the script.</p>
740:
741: </dd>
742:
743:
744: <dt id="script-processing-src">If the element has a <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute</dt>
745:
746: <dd>
747:
748: <p>The element must be added to the <dfn id="set-of-scripts-that-will-execute-as-soon-as-possible">set of scripts that
1.20 mike 749: will execute as soon as possible</dfn> of the
750: <code><a href="infrastructure.html#document">Document</a></code> of the <code><a href="#script">script</a></code> element at the
751: time the <a href="#running-a-script">running a script</a> algorithm started.</p>
1.1 mike 752:
753: <p>The <a href="webappapis.html#concept-task" title="concept-task">task</a> that the
754: <a href="webappapis.html#networking-task-source">networking task source</a> places on the <a href="webappapis.html#task-queue">task
755: queue</a> once the <a href="fetching-resources.html#fetch" title="fetch">fetching
756: algorithm</a> has completed must <a href="#executing-a-script-block" title="executing a
757: script block">execute the script block</a> and then remove
758: the element from the <a href="#set-of-scripts-that-will-execute-as-soon-as-possible">set of scripts that will execute as
759: soon as possible</a>.</p>
760:
761: </dd>
762:
763:
764: <dt id="script-processing-inline">Otherwise</dt>
765:
766: <dd>The user agent must immediately <a href="#executing-a-script-block" title="executing a
767: script block">execute the script block</a>, even if other
768: scripts are already executing.</dd>
769:
770: </dl></li>
771:
772: </ol><!-- similar text in various places --><p>Fetching an external script must <a href="the-end.html#delay-the-load-event">delay the load
773: event</a> of the element's document until the <a href="webappapis.html#concept-task" title="concept-task">task</a> that is <a href="webappapis.html#queue-a-task" title="queue a
774: task">queued</a> by the <a href="webappapis.html#networking-task-source">networking task source</a> once
775: the resource has been <a href="fetching-resources.html#fetch" title="fetch">fetched</a> (defined
776: above) has been run.</p>
777:
1.20 mike 778: <p>The <dfn id="pending-parsing-blocking-script">pending parsing-blocking script</dfn> of a
779: <code><a href="infrastructure.html#document">Document</a></code> is used by the <code><a href="infrastructure.html#document">Document</a></code>'s
780: parser(s).</p>
1.1 mike 781:
1.26 mike 782: <p class="note">If a <code><a href="#script">script</a></code> element that blocks a
783: parser gets moved to another <code><a href="infrastructure.html#document">Document</a></code> before it would
784: normally have stopped blocking that parser, it nonetheless continues
785: blocking that parser until the condition that causes it to be
786: blocking the parser no longer applies (e.g. if the script is a
787: <a href="#pending-parsing-blocking-script">pending parsing-blocking script</a> because there was
788: <a href="semantics.html#a-style-sheet-that-is-blocking-scripts">a style sheet that is blocking scripts</a> when it was
789: parsed, but then the script is moved to another
790: <code><a href="infrastructure.html#document">Document</a></code> before the style sheet loads, the script still
791: blocks the parser until the style sheets are all loaded, at which
792: time the script executes and the parser is unblocked).</p>
793:
794: <!-- also (and this would be worth testing): the way the spec is
795: written, if you do not have a style sheet that is blocking scripts,
796: then you parse a <script src>, then while waiting for the script to
797: load you insert an external style sheet, the script will delay until
798: the sheet is loaded, because there's just a binary "are style sheets
799: blocking scripts" state, things aren't defined in terms of which
800: style sheets are blocking which scripts -->
801:
1.1 mike 802: <p><dfn id="executing-a-script-block" title="executing a script block">Executing a script
803: block</dfn>: When the steps above require that the script block be
804: executed, the user agent must act as follows:</p>
805:
806: <dl class="switch"><dt>If the load resulted in an error (for example a DNS error, or
807: an HTTP 404 error)</dt>
808:
809: <dd><p>Executing the script block must just consist of <a href="webappapis.html#fire-a-simple-event" title="fire a simple event">firing a simple event</a> named
810: <code title="event-error">error</code> at the element.</p></dd>
811:
812: <dt>If the load was successful</dt>
813:
814: <!-- SCRIPT EXEC -->
815: <dd>
816:
1.27 mike 817: <p>Executing the script block must consists of running the
818: following steps. For the purposes of these steps, the script is
819: considered to be from an <i>external file</i> if, while the
820: <a href="#running-a-script">running a script</a> algorithm above was running for this
821: script, the <code><a href="#script">script</a></code> element had a <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute specified.</p>
822:
1.1 mike 823: <ol><li>
824:
825: <p>Initialize <dfn id="the-script-block-s-source"><var>the script block's source</var></dfn> as
826: follows:</p>
827:
828: <dl class="switch"><dt>If the script is from an external file and <var><a href="#the-script-block-s-type">the script block's type</a></var> is a text-based language</dt>
829:
830: <dd>
831:
832: <p>The contents of that file, interpreted as string of
833: Unicode characters, are the script source.</p>
834:
1.23 mike 835: <p>To obtain the string of Unicode characters, the user agent
836: run the following steps:</p>
1.1 mike 837:
1.23 mike 838: <ol><li><p>If the resource's <a href="fetching-resources.html#content-type" title="Content-Type">Content
839: Type metadata</a>, if any, specifies a character encoding,
840: and the user agent supports that encoding, then let <var title="">character encoding</var> be that encoding, and jump
841: to the bottom step in this series of steps.</p></li>
842:
843: <li><p>If the algorithm above set <var><a href="#the-script-block-s-character-encoding">the script block's
844: character encoding</a></var>, then let <var title="">character
845: encoding</var> be that encoding, and jump to the bottom step
846: in this series of steps.</p></li>
847:
848: <li><p>For each of the rows in the following table, starting
849: with the first one and going down, if the file has as many or
850: more bytes available than the number of bytes in the first
851: column, and the first bytes of the file match the bytes given
852: in the first column, then set <var title="">character
853: encoding</var> to the encoding given in the cell in the
854: second column of that row, and jump to the bottom step in
855: this series of steps:</p>
856:
857: <!-- this table is present in several forms in this file; keep them in sync -->
858: <table id="table-script-bom"><thead><tr><th>Bytes in Hexadecimal
859: </th><th>Encoding
860: </th></tr></thead><tbody><!-- nobody uses this
861: <tr>
862: <td>00 00 FE FF
863: <td>UTF-32BE
864: <tr>
865: <td>FF FE 00 00
866: <td>UTF-32LE
867: --><tr><td>FE FF
868: </td><td>Big-endian UTF-16
869: </td></tr><tr><td>FF FE
870: </td><td>Little-endian UTF-16
871: </td></tr><tr><td>EF BB BF
872: </td><td>UTF-8
873: <!-- nobody uses this
874: <tr>
875: <td>DD 73 66 73
876: <td>UTF-EBCDIC
877: -->
878: </td></tr></tbody></table><p class="note">This step looks for Unicode Byte Order Marks
879: (BOMs).</p>
880:
881: </li>
882:
883: <li><p>Let <var title="">character encoding</var> be <var><a href="#the-script-block-s-fallback-character-encoding">the
884: script block's fallback character encoding</a></var>.</p></li>
885:
886: <li><p>Convert the file to Unicode using <var>character
887: encoding</var>, following the rules for doing so given by the
888: specification for <var><a href="#the-script-block-s-type">the script block's
889: type</a></var>.</p></li>
890:
891: </ol></dd>
1.1 mike 892:
893: <dt>If the script is from an external file and <var><a href="#the-script-block-s-type">the script block's type</a></var> is an XML-based language</dt>
894:
895: <dd>
896:
897: <p>The external file is the script source. When it is later
898: executed, it must be interpreted in a manner consistent with
899: the specification defining the language given by <var><a href="#the-script-block-s-type">the
900: script block's type</a></var>.</p>
901:
902: </dd>
903:
904: <dt>If the script is inline and <var><a href="#the-script-block-s-type">the script block's type</a></var> is a text-based language</dt>
905:
906: <dd>
907:
908: <p>The value of the <code title="dom-script-text"><a href="#dom-script-text">text</a></code>
909: IDL attribute at the time the element's <a href="#already-started">"already
910: started"</a> flag was set is the script source.</p>
911:
912: </dd>
913:
914: <dt>If the script is inline and <var><a href="#the-script-block-s-type">the script block's type</a></var> is an XML-based language</dt>
915:
916: <dd>
917:
918: <p>The child nodes of the <code><a href="#script">script</a></code> element at the
919: time the element's <a href="#already-started">"already started"</a> flag was set
920: are the script source.</p>
921:
922: </dd>
923:
924: </dl></li>
925:
926: <li>
927:
1.27 mike 928: <p>If the script is from an external file, then increment the
929: <a href="apis-in-html-documents.html#ignore-destructive-writes-counter">ignore-destructive-writes counter</a> of the
930: <code><a href="#script">script</a></code> element's <code><a href="infrastructure.html#document">Document</a></code>. Let <var title="">neutralized doc</var> be that
1.7 mike 931: <code><a href="infrastructure.html#document">Document</a></code>.</p>
932:
933: </li>
934:
935: <li>
936:
1.1 mike 937: <p><a href="webappapis.html#create-a-script-from-a-node" title="create a script from a node">Create a
938: script</a> from the <code><a href="#script">script</a></code> element node, using
939: <var><a href="#the-script-block-s-source">the script block's source</a></var> and <var><a href="#the-script-block-s-type">the script
940: block's type</a></var>.</p>
941:
942: <p class="note">This is where the script is compiled and
943: actually executed.</p>
944:
945: </li>
946:
947: <li>
948:
1.27 mike 949: <p>Decrement the <a href="apis-in-html-documents.html#ignore-destructive-writes-counter">ignore-destructive-writes counter</a>
950: of <var title="">neutralized doc</var>, if it was incremented in
951: the earlier step.</p>
1.7 mike 952:
953: </li>
954:
955: <li>
956:
1.1 mike 957: <p>If the script is from an external file, <a href="webappapis.html#fire-a-simple-event">fire a simple
958: event</a> named <code title="event-load">load</code> at the
959: <code><a href="#script">script</a></code> element.</p>
960:
961: <p>Otherwise, the script is internal; <a href="webappapis.html#queue-a-task">queue a task</a>
962: to <a href="webappapis.html#fire-a-simple-event">fire a simple event</a> named <code title="event-load">load</code> at the <code><a href="#script">script</a></code>
963: element.</p>
964:
965: </li>
966:
967: </ol></dd>
968:
969: </dl><p>The IDL attributes <dfn id="dom-script-src" title="dom-script-src"><code>src</code></dfn>, <dfn id="dom-script-type" title="dom-script-type"><code>type</code></dfn>, <dfn id="dom-script-charset" title="dom-script-charset"><code>charset</code></dfn>, <dfn id="dom-script-async" title="dom-script-async"><code>async</code></dfn>, and <dfn id="dom-script-defer" title="dom-script-defer"><code>defer</code></dfn>, each must
970: <a href="common-dom-interfaces.html#reflect">reflect</a> the respective content attributes of the same
971: name.</p>
972:
973: </div><dl class="domintro"><dt><var title="">script</var> . <code title="dom-script-text"><a href="#dom-script-text">text</a></code> [ = <var title="">value</var> ]</dt>
974:
975: <dd>
976:
977: <p>Returns the contents of the element, ignoring child nodes that
978: aren't <a href="infrastructure.html#text-node" title="text node">text nodes</a>.</p>
979:
980: <p>Can be set, to replace the element's children with the given
981: value.</p>
982:
983: </dd>
984:
985: </dl><div class="impl">
986:
987: <p>The IDL attribute <dfn id="dom-script-text" title="dom-script-text"><code>text</code></dfn> must return a
988: concatenation of the contents of all the <a href="infrastructure.html#text-node" title="text
989: node">text nodes</a> that are direct children of the
990: <code><a href="#script">script</a></code> element (ignoring any other nodes such as
991: comments or elements), in tree order. On setting, it must act the
992: same way as the <code><a href="infrastructure.html#textcontent">textContent</a></code> IDL attribute.</p>
993:
994: </div><p class="note">When inserted using the <code title="dom-document-write"><a href="apis-in-html-documents.html#dom-document-write">document.write()</a></code> method,
995: <code><a href="#script">script</a></code> elements execute (typically synchronously), but
996: when inserted using <code title="dom-innerHTML"><a href="apis-in-html-documents.html#dom-innerhtml">innerHTML</a></code> and <code title="dom-outerHTML"><a href="apis-in-html-documents.html#dom-outerhtml">outerHTML</a></code> attributes, they do not
997: execute at all.</p><div class="example">
998:
999: <p>In this example, two <code><a href="#script">script</a></code> elements are used. One
1000: embeds an external script, and the other includes some data.</p>
1001:
1002: <pre><script src="game-engine.js"></script>
1003: <script type="text/x-game-map">
1004: ........U.........e
1005: o............A....e
1006: .....A.....AAA....e
1007: .A..AAA...AAAAA...e
1008: </script></pre>
1009:
1010: <p>The data in this case might be used by the script to generate
1011: the map of a video game. The data doesn't have to be used that way,
1012: though; maybe the map data is actually embedded in other parts of
1013: the page's markup, and the data block here is just used by the
1014: site's search engine to help users who are looking for particular
1015: features in their game maps.</p>
1016:
1017: </div><div class="example">
1018:
1019: <p>The following sample shows how a script element can be used to
1020: define a function that is then used by other parts of the
1021: document. It also shows how a <code><a href="#script">script</a></code> element can be
1022: used to invoke script while the document is being parsed, in this
1023: case to initialize the form's output.</p>
1024:
1025: <pre><script>
1026: function calculate(form) {
1027: var price = 52000;
1028: if (form.elements.brakes.checked)
1029: price += 1000;
1030: if (form.elements.radio.checked)
1031: price += 2500;
1032: if (form.elements.turbo.checked)
1033: price += 5000;
1034: if (form.elements.sticker.checked)
1035: price += 250;
1036: form.elements.result.value = price;
1037: }
1038: </script>
1039: <form name="pricecalc" onsubmit="return false">
1040: <fieldset>
1041: <legend>Work out the price of your car</legend>
1042: <p>Base cost: £52000.</p>
1043: <p>Select additional options:</p>
1044: <ul>
1045: <li><label><input type=checkbox name=brakes> Ceramic brakes (£1000)</label></li>
1046: <li><label><input type=checkbox name=radio> Satellite radio (£2500)</label></li>
1047: <li><label><input type=checkbox name=turbo> Turbo charger (£5000)</label></li>
1048: <li><label><input type=checkbox name=sticker> "XZ" sticker (£250)</label></li>
1049: </ul>
1050: <p>Total: £<output name=result onformchange="calculate(form)"></output></p>
1051: </fieldset>
1052: <script>
1053: document.forms.pricecalc.dispatchFormChange();
1054: </script>
1055: </form></pre>
1056:
1.15 mike 1057: </div><h5 id="scriptingLanguages"><span class="secno">4.3.1.1 </span>Scripting languages</h5><div class="impl">
1.1 mike 1058:
1059: <p>A user agent is said to <dfn id="support-the-scripting-language">support the scripting language</dfn>
1060: if <var><a href="#the-script-block-s-type">the script block's type</a></var> is an <a href="infrastructure.html#ascii-case-insensitive">ASCII
1061: case-insensitive</a> match for the <a href="infrastructure.html#mime-type">MIME type</a> string
1062: of a scripting language that the user agent implements.</p>
1063:
1064: </div><p>The following lists some <a href="infrastructure.html#mime-type">MIME type</a> strings and the
1065: languages to which they refer:</p><dl><dt>"<code>application/ecmascript</code>"</dt>
1066: <dt>"<code>application/javascript</code>"</dt>
1067: <dt>"<code>application/x-ecmascript</code>"</dt>
1068: <dt>"<code>application/x-javascript</code>"</dt>
1069: <dt>"<code>text/ecmascript</code>"</dt>
1070: <dt>"<code>text/javascript</code>"</dt>
1071: <dt>"<code>text/javascript1.0</code>"</dt>
1072: <dt>"<code>text/javascript1.1</code>"</dt>
1073: <dt>"<code>text/javascript1.2</code>"</dt>
1074: <dt>"<code>text/javascript1.3</code>"</dt>
1075: <dt>"<code>text/javascript1.4</code>"</dt>
1076: <dt>"<code>text/javascript1.5</code>"</dt>
1077: <dt>"<code>text/jscript</code>"</dt>
1078: <dt>"<code>text/livescript</code>"</dt>
1079: <dt>"<code>text/x-ecmascript</code>"</dt>
1080: <dt>"<code>text/x-javascript</code>"</dt>
1081: <dd>JavaScript. <a href="references.html#refsECMA262">[ECMA262]</a></dd>
1082:
1083: <dt>"<code>text/javascript;e4x=1</code>"</dt>
1084: <dd>JavaScript with ECMAScript for XML. <a href="references.html#refsECMA357">[ECMA357]</a></dd>
1085:
1086: </dl><div class="impl">
1087:
1088: <p>User agents may support other <a href="infrastructure.html#mime-type" title="MIME type">MIME
1089: types</a> and other languages.</p>
1090:
1091: <!-- this paragraph is also present in the <style type="text/css"> section -->
1092: <p>When examining types to determine if they support the language,
1093: user agents must not ignore unknown MIME parameters — types
1094: with unknown parameters must be assumed to be unsupported. The <code title="">charset</code> parameter must be treated as an unknown
1095: parameter for the purpose of comparing <a href="infrastructure.html#mime-type" title="MIME type">MIME
1096: types</a> here.</p>
1097:
1.15 mike 1098: </div><h5 id="restrictions-for-contents-of-script-elements"><span class="secno">4.3.1.2 </span><dfn title="script content restrictions">Restrictions for contents of <code>script</code> elements</dfn></h5><p>The <code><a href="infrastructure.html#textcontent">textContent</a></code> of a <code><a href="#script">script</a></code> element must match the
1.1 mike 1099: <code title="">script</code> production in the following ABNF, the
1100: character set for which is Unicode. <a href="references.html#refsABNF">[ABNF]</a></p><pre>script = data1 *( escape [ script-start data3 ] "-->" data1 ) [ escape ]
1101: escape = "<!--" data2 *( script-start data3 script-end data2 )
1102:
1103: data1 = <any string that doesn't contain a substring that matches not-data1>
1104: not-data1 = <!-- script-end / -->"<!--" <!-- the script-end is redundant here since it would close the element -->
1105:
1106: data2 = <any string that doesn't contain a substring that matches not-data2>
1107: not-data2 = <!-- script-end / -->script-start / "-->" <!-- the script-end is redundant here since it would close the element -->
1108:
1109: data3 = <any string that doesn't contain a substring that matches not-data3>
1110: not-data3 = script-end / "-->"
1111:
1112: script-start = lt s c r i p t tag-end
1113: script-end = lt slash s c r i p t tag-end
1114:
1115: lt = %x003C ; U+003C LESS-THAN SIGN character (<)
1116: slash = %x002F ; U+002F SOLIDUS character (/)
1117:
1118: s = %x0053 ; U+0053 LATIN CAPITAL LETTER S
1119: s =/ %x0073 ; U+0073 LATIN SMALL LETTER S
1120: c = %x0043 ; U+0043 LATIN CAPITAL LETTER C
1121: c =/ %x0063 ; U+0063 LATIN SMALL LETTER C
1122: r = %x0052 ; U+0052 LATIN CAPITAL LETTER R
1123: r =/ %x0072 ; U+0072 LATIN SMALL LETTER R
1124: i = %x0049 ; U+0049 LATIN CAPITAL LETTER I
1125: i =/ %x0069 ; U+0069 LATIN SMALL LETTER I
1126: p = %x0050 ; U+0050 LATIN CAPITAL LETTER P
1127: p =/ %x0070 ; U+0070 LATIN SMALL LETTER P
1128: t = %x0054 ; U+0054 LATIN CAPITAL LETTER T
1129: t =/ %x0074 ; U+0074 LATIN SMALL LETTER T
1130:
1131: tag-end = %x0009 ; U+0009 CHARACTER TABULATION
1132: tag-end =/ %x000A ; U+000A LINE FEED (LF)
1133: tag-end =/ %x000C ; U+000C FORM FEED (FF)
1134: tag-end =/ %x0020 ; U+0020 SPACE
1135: tag-end =/ %x002F ; U+002F SOLIDUS (/)
1136: tag-end =/ %x003E ; U+003E GREATER-THAN SIGN (>)</pre><p>When a <code><a href="#script">script</a></code> element contains <a href="#inline-documentation-for-external-scripts">script
1137: documentation</a>, there are further restrictions on the contents
1.15 mike 1138: of the element, as described in the section below.</p><h5 id="inline-documentation-for-external-scripts"><span class="secno">4.3.1.3 </span><dfn title="script documentation">Inline documentation for external scripts</dfn></h5><p>If a <code><a href="#script">script</a></code> element's <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute is specified, then the
1.1 mike 1139: contents of the <code><a href="#script">script</a></code> element, if any, must be such
1140: that the value of the <code title="dom-script-text"><a href="#dom-script-text">text</a></code> IDL
1141: attribute, which is derived from the element's contents, matches the
1142: <code title="">documentation</code> production in the following
1143: ABNF, the character set for which is Unicode. <a href="references.html#refsABNF">[ABNF]</a></p><pre>documentation = *( *( space / tab / comment ) [ line-comment ] newline )
1144: comment = slash star *( not-star / star not-slash ) 1*star slash
1145: line-comment = slash slash *not-newline
1146:
1147: ; characters
1148: tab = %x0009 ; U+0009 TAB
1149: newline = %x000A ; U+000A LINE FEED (LF)
1150: space = %x0020 ; U+0020 SPACE
1151: star = %x002A ; U+002A ASTERISK (*)
1152: slash = %x002F ; U+002F SOLIDUS (/)
1153: not-newline = %x0000-0009 / %x000B-10FFFF
1154: ; a Unicode character other than U+000A LINE FEED (LF)
1155: not-star = %x0000-0029 / %x002B-10FFFF
1156: ; a Unicode character other than U+002A ASTERISK (*)
1157: not-slash = %x0000-002E / %x0030-10FFFF
1158: ; a Unicode character other than U+002F SOLIDUS (/)</pre><p class="note">This corresponds to putting the contents of the
1159: element in JavaScript comments.</p><p class="note">This requirement is in addition to the earlier
1160: restrictions on the syntax of contents of <code><a href="#script">script</a></code>
1161: elements.</p><div class="example">
1162:
1163: <p>This allows authors to include documentation, such as license
1164: information or API information, inside their documents while still
1165: referring to external script files. The syntax is constrained so
1166: that authors don't accidentally include what looks like valid
1167: script while also providing a <code title="attr-script-src"><a href="#attr-script-src">src</a></code> attribute.</p>
1168:
1169: <pre><script src="cool-effects.js">
1170: // create new instances using:
1171: // var e = new Effect();
1172: // start the effect using .play, stop using .stop:
1173: // e.play();
1174: // e.stop();
1175: </script></pre>
1176:
1.22 mike 1177: </div><h4 id="the-noscript-element"><span class="secno">4.3.2 </span>The <dfn><code>noscript</code></dfn> element</h4><dl class="element"><dt>Categories</dt>
1.1 mike 1178: <dd><a href="content-models.html#metadata-content">Metadata content</a>.</dd>
1179: <dd><a href="content-models.html#flow-content">Flow content</a>.</dd>
1180: <dd><a href="content-models.html#phrasing-content">Phrasing content</a>.</dd>
1.16 mike 1181: <dt>Contexts in which this element can be used:</dt>
1.1 mike 1182: <dd>In a <code><a href="semantics.html#the-head-element-0">head</a></code> element of an <a href="dom.html#html-documents" title="HTML documents">HTML document</a>, if there are no ancestor <code><a href="#the-noscript-element">noscript</a></code> elements.</dd>
1183: <dd>Where <a href="content-models.html#phrasing-content">phrasing content</a> is expected in <a href="dom.html#html-documents">HTML documents</a>, if there are no ancestor <code><a href="#the-noscript-element">noscript</a></code> elements.</dd>
1184: <dt>Content model:</dt>
1185: <dd>When <a href="webappapis.html#concept-n-noscript" title="concept-n-noscript">scripting is disabled</a>, in a <code><a href="semantics.html#the-head-element-0">head</a></code> element: in any order, zero or more <code><a href="semantics.html#the-link-element">link</a></code> elements, zero or more <code><a href="semantics.html#the-style-element">style</a></code> elements, and zero or more <code><a href="semantics.html#meta">meta</a></code> elements.</dd>
1186: <dd>When <a href="webappapis.html#concept-n-noscript" title="concept-n-noscript">scripting is disabled</a>, not in a <code><a href="semantics.html#the-head-element-0">head</a></code> element: <a href="content-models.html#transparent">transparent</a>, but there must be no <code><a href="#the-noscript-element">noscript</a></code> element descendants.</dd>
1187: <dd>Otherwise: text that conforms to the requirements given in the prose.</dd>
1188: <dt>Content attributes:</dt>
1189: <dd><a href="elements.html#global-attributes">Global attributes</a></dd>
1190: <dt>DOM interface:</dt>
1191: <dd>Uses <code><a href="elements.html#htmlelement">HTMLElement</a></code>.</dd>
1192: </dl><p>The <code><a href="#the-noscript-element">noscript</a></code> element <a href="rendering.html#represents">represents</a> nothing
1193: if <a href="webappapis.html#concept-n-script" title="concept-n-script">scripting is enabled</a>, and
1194: <a href="rendering.html#represents">represents</a> its children if <a href="webappapis.html#concept-n-noscript" title="concept-n-noscript">scripting is disabled</a>. It is used
1195: to present different markup to user agents that support scripting
1196: and those that don't support scripting, by affecting how the
1197: document is parsed.</p><p>When used in <a href="dom.html#html-documents">HTML documents</a>, the allowed content
1198: model is as follows:</p><dl><dt>In a <code><a href="semantics.html#the-head-element-0">head</a></code> element, if <a href="webappapis.html#concept-n-noscript" title="concept-n-noscript">scripting is disabled</a> for the
1199: <code><a href="#the-noscript-element">noscript</a></code> element</dt>
1200:
1201: <dd><p>The <code><a href="#the-noscript-element">noscript</a></code> element must contain only
1202: <code><a href="semantics.html#the-link-element">link</a></code>, <code><a href="semantics.html#the-style-element">style</a></code>, and <code><a href="semantics.html#meta">meta</a></code>
1203: elements.</p></dd>
1204:
1205: <dt>In a <code><a href="semantics.html#the-head-element-0">head</a></code> element, if <a href="webappapis.html#concept-n-script" title="concept-n-script">scripting is enabled</a> for the
1206: <code><a href="#the-noscript-element">noscript</a></code> element</dt>
1207:
1208: <dd><p>The <code><a href="#the-noscript-element">noscript</a></code> element must contain only text,
1209: except that invoking the <a href="the-end.html#html-fragment-parsing-algorithm">HTML fragment parsing
1210: algorithm</a> <!-- (which disables <script type="text/javascript"> execution) --> with
1211: the <code><a href="#the-noscript-element">noscript</a></code> element as the <var title="">context</var> element and the text contents as the <var title="">input</var> must result in a list of nodes that consists
1212: only of <code><a href="semantics.html#the-link-element">link</a></code>, <code><a href="semantics.html#the-style-element">style</a></code>, and
1213: <code><a href="semantics.html#meta">meta</a></code> elements that would be conforming if they were
1214: children of the <code><a href="#the-noscript-element">noscript</a></code> element, and no <a href="parsing.html#parse-error" title="parse error">parse errors</a>.</p></dd>
1215:
1216: <dt>Outside of <code><a href="semantics.html#the-head-element-0">head</a></code> elements, if <a href="webappapis.html#concept-n-noscript" title="concept-n-noscript">scripting is disabled</a> for the
1217: <code><a href="#the-noscript-element">noscript</a></code> element</dt>
1218:
1219: <dd><p>The <code><a href="#the-noscript-element">noscript</a></code> element's content model is
1220: <a href="content-models.html#transparent">transparent</a>, with the additional restriction that a
1221: <code><a href="#the-noscript-element">noscript</a></code> element must not have a <code><a href="#the-noscript-element">noscript</a></code>
1222: element as an ancestor (that is, <code><a href="#the-noscript-element">noscript</a></code> can't be
1223: nested).</p></dd>
1224:
1225: <dt>Outside of <code><a href="semantics.html#the-head-element-0">head</a></code> elements, if <a href="webappapis.html#concept-n-script" title="concept-n-script">scripting is enabled</a> for the
1226: <code><a href="#the-noscript-element">noscript</a></code> element</dt>
1227:
1228: <dd>
1229:
1230: <p>The <code><a href="#the-noscript-element">noscript</a></code> element must contain only text,
1231: except that the text must be such that running the following
1232: algorithm results in a conforming document with no
1233: <code><a href="#the-noscript-element">noscript</a></code> elements and no <code><a href="#script">script</a></code>
1234: elements, and such that no step in the algorithm causes an
1235: <a href="parsing.html#html-parser">HTML parser</a> to flag a <a href="parsing.html#parse-error">parse error</a>:</p>
1236:
1237: <ol><li>Remove every <code><a href="#script">script</a></code> element from the
1238: document.</li>
1239:
1240: <li>Make a list of every <code><a href="#the-noscript-element">noscript</a></code> element in the
1241: document. For every <code><a href="#the-noscript-element">noscript</a></code> element in that list,
1242: perform the following steps:
1243:
1244: <ol><li>Let the <var title="">parent element</var> be the parent
1245: element of the <code><a href="#the-noscript-element">noscript</a></code> element.</li>
1246:
1247: <li>Take all the children of the <var title="">parent element</var>
1248: that come before the <code><a href="#the-noscript-element">noscript</a></code> element, and call these
1249: elements <var title="">the before children</var>.</li>
1250:
1251: <li>Take all the children of the <var title="">parent element</var>
1252: that come <em>after</em> the <code><a href="#the-noscript-element">noscript</a></code> element, and
1253: call these elements <var title="">the after children</var>.</li>
1254:
1255: <li>Let <var title="">s</var> be the concatenation of all the
1256: <a href="infrastructure.html#text-node">text node</a> children of the <code><a href="#the-noscript-element">noscript</a></code>
1257: element.</li>
1258:
1259: <li>Set the <code title="dom-innerHTML"><a href="apis-in-html-documents.html#dom-innerhtml">innerHTML</a></code>
1260: attribute of the <var title="">parent element</var> to the value
1261: of <var title="">s</var>. (This, as a side-effect, causes the
1262: <code><a href="#the-noscript-element">noscript</a></code> element to be removed from the
1263: document.)</li>
1264:
1265: <li>Insert <var title="">the before children</var> at the start of
1266: the <var title="">parent element</var>, preserving their original
1267: relative order.</li>
1268:
1269: <li>Insert <var title="">the after children</var> at the end of the
1270: <var title="">parent element</var>, preserving their original
1271: relative order.</li>
1272:
1273: </ol></li>
1274:
1275: </ol></dd>
1276:
1277: </dl><p class="note">All these contortions are required because, for
1278: historical reasons, the <code><a href="#the-noscript-element">noscript</a></code> element is handled
1279: differently by the <a href="parsing.html#html-parser">HTML parser</a> based on whether <a href="parsing.html#scripting-flag" title="scripting flag">scripting was enabled or not</a> when the
1280: parser was invoked.</p><p>The <code><a href="#the-noscript-element">noscript</a></code> element must not be used in <a href="dom.html#xml-documents">XML
1281: documents</a>.</p><p class="note"><strong>The <code><a href="#the-noscript-element">noscript</a></code> element is only
1282: effective in <a href="syntax.html#syntax">the HTML syntax</a>, it has no effect in
1283: <a href="the-xhtml-syntax.html#the-xhtml-syntax">the XHTML syntax</a>.</strong></p><div class="impl">
1284:
1285: <p>The <code><a href="#the-noscript-element">noscript</a></code> element has no other requirements. In
1286: particular, children of the <code><a href="#the-noscript-element">noscript</a></code> element are not
1287: exempt from <a href="association-of-controls-and-forms.html#form-submission">form submission</a>, scripting, and so forth,
1288: even when <a href="webappapis.html#concept-n-script" title="concept-n-script">scripting is enabled</a>
1289: for the element.</p>
1290:
1291: </div><div class="example">
1292:
1293: <p>In the following example, a <code><a href="#the-noscript-element">noscript</a></code> element is
1294: used to provide fallback for a script.</p>
1295:
1296: <pre><form action="calcSquare.php">
1297: <p>
1298: <label for=x>Number</label>:
1299: <input id="x" name="x" type="number">
1300: </p>
1301: <script>
1302: var x = document.getElementById('x');
1303: var output = document.createElement('p');
1304: output.textContent = 'Type a number; it will be squared right then!';
1305: x.form.appendChild(output);
1306: x.form.onsubmit = function () { return false; }
1307: x.oninput = function () {
1308: var v = x.valueAsNumber;
1309: output.textContent = v + ' squared is ' + v * v;
1310: };
1311: </script>
1312: <noscript>
1313: <input type=submit value="Calculate Square">
1314: </noscript>
1315: </form></pre>
1316:
1317: <p>When script is disabled, a button appears to do the calculation
1318: on the server side. When script is enabled, the value is computed
1319: on-the-fly instead.</p>
1320:
1321: <p>The <code><a href="#the-noscript-element">noscript</a></code> element is a blunt
1322: instrument. Sometimes, scripts might be enabled, but for some
1323: reason the page's script might fail. For this reason, it's
1324: generally better to avoid using <code><a href="#the-noscript-element">noscript</a></code>, and to
1325: instead design the script to change the page from being a
1326: scriptless page to a scripted page on the fly, as in the next
1327: example:</p>
1328:
1329: <pre><form action="calcSquare.php">
1330: <p>
1331: <label for=x>Number</label>:
1332: <input id="x" name="x" type="number">
1333: </p>
1334: <strong><input id="submit" type=submit value="Calculate Square"></strong>
1335: <script>
1336: var x = document.getElementById('x');
1337: var output = document.createElement('p');
1338: output.textContent = 'Type a number; it will be squared right then!';
1339: x.form.appendChild(output);
1340: x.form.onsubmit = function () { return false; }
1341: x.oninput = function () {
1342: var v = x.valueAsNumber;
1343: output.textContent = v + ' squared is ' + v * v;
1344: };
1345: <strong> var submit = document.getElementById('submit');
1346: submit.parentNode.removeChild(submit);</strong>
1347: </script>
1348: </form></pre>
1349:
1350: <p>The above technique is also useful in XHTML, since
1351: <code><a href="#the-noscript-element">noscript</a></code> is not supported in <a href="the-xhtml-syntax.html#the-xhtml-syntax">the XHTML
1352: syntax</a>.</p>
1353:
1354: </div></body></html>
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