Legacy DOM events are no longer supported

Microsoft identifies features as deprecated to warn against using the features in the future so that they can be phased out.

• If new standards-based support is added in Windows Internet Explorer 9, the associated feature documentation on MSDN is marked with "deprecated" and includes a link to the standards-based alternative.
• If the feature is a web platform feature, it is supported across all document modes until the feature is shown to be used by very few websites.

Certain legacy Document Object Model (DOM) events features are deprecated in IE9 Standards mode and are intended to be removed in the latest standards mode of the next major release. Here are the deprecated events and the standards-based alternatives you should use instead:

Deprecated feature	W3C standards replacement
attachEvent	addEventListener
detachEvent	removeEventListener
createEventObject	createEvent
fireEvent	dispatchEvent

 

As of Internet Explorer 11, these events are considered obsolete in edge mode and are no longer supported.