Check if the given string is an absolute URL

Use RegExp.prototype.test() to test if the string is an absolute URL.

const isAbsoluteURL = str => /^[a-z][a-z0-9+.-]*:/.test(str);

// EXAMPLES
isAbsoluteURL('https://google.com'); // true
isAbsoluteURL('ftp://www.myserver.net'); // true
isAbsoluteURL('/foo/bar'); // false

Source

https://www.30secondsofcode.org/js/s/is-absolute-url