January 6, 2000 - Cross-Browser Event Handler

January 6, 2000 Cross-Browser Event Handler Tips: January 2000 Yehuda Shiran, Ph.D. Doc JavaScript

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Although Navigator 4.0x greatly expanded its set of elements that generate events, the selection is still much more limited. Not all elements can be the source of a mouse or keyboard event. For comparison, here's a list of the elements that support the onmouseup event handler in Navigator 4.0x:

Needless to say, there are only several elements that accept the onmouseup event handler in Navigator 4.0x and up. There is obviously no way to specify an event handler for an element that doesn't support it. Since Internet Explorer 4.0x and up normally features much more elements that support a given event handler, you should only use those that are also supported by Navigator 4.0x and up when writing a cross-browser script. In any case, if you add an event handler to an element that doesn't support that type of event handler, it has no effect. Regardless of whether you specify the event handler as a property or as an HTML attribute, the browser does not generate an error (because HTML never causes explicit errors, and adding a new property to an existing object is a legal JavaScript operation). For example, Navigator 4.0x and up ignores the following event handler specification, whereas Internet Explorer 4.0x and up supports it:

<P onClick="alert('This only works with Internet Explorer 4.0x.')"></P>

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