How to reference the caller object (“this”) using attachEvent

From this quirksmode article with regard to attachEvent:

  1. Events always bubble, no capturing possibility.
  2. The event handling function is referenced, not copied, so the this keyword always refers to the window and is completely useless.

The result of these two weaknesses is that when an event bubbles up it is impossible to know which HTML element currently handles the event. I explain this problem more fully on the Event order page.

Since the Microsoft event adding model is only supported by Explorer 5 and higher on Windows, it cannot be used for cross–browser scripts. But even for Explorer–on–Windows only applications it’s best not to use it, since the bubbling problem can be quite nasty in complex applications.

I haven’t tested it, but a possible workaround may be to wrap the handler in an anonymous function that calls your handler via funct.call().

else if(element.attachEvent){
   element.attachEvent("on"+name, function(){ funct.call( element ) });
}

My apologies for the untested solution. I don’t like doing that, but can’t easily get to IE right now.

Leave a Comment