Debug JavaScript in Internet Explorer

The most basic way to track down errors is by turning on error information in your browser. By default, Internet Explorer shows an error icon in the status bar when an error occurs on the page. 

Double-clicking this icon takes you to a dialog box showing information about the specific error that occurred. Since this icon is easy to overlook, Internet Explorer gives you the option to automatically show the Error dialog box whenever an error occurs. 

To enable this option, select Tools → Internet Options → Advanced tab. and then finally check the "Display a Notification About Every Script Error" box option as shown below −