Dynamic Function Reference in Javascript

January 10, 2007 7:54 AM

I'm writing a cross-browser JavaScript library that will allow me to apply events (onmouseover, click, etc) to elements using what look like stylesheets:

a {mouseover:someFunction;}

In writing a parser for these files, I've come upon a stumbling block.

How does one reference a function given by a String? Or rather, in

element.onmouseover = someFunction

how would one let someFunction be a variable?

posted by potch to Computers & Internet (10 answers total)

eval()
posted by grouse at 8:01 AM on January 10, 2007

eval() maybe ?

Have you looked at the code of the (excellent) competition ?I'm thinking of the Behaviour lib, or LowPro, JQuery, etc

Good luck.
posted by androse at 8:03 AM on January 10, 2007

Response by poster: I was hoping not to have to use eval(), simply because of the possibility for misuse.
posted by potch at 8:04 AM on January 10, 2007

Best answer: Actually, you probably want new Function() instead. Sorry.
posted by grouse at 8:04 AM on January 10, 2007

Response by poster: Here's a little more information: The library is written to work hand-in-hand with Prototype.js, and all its buzzworthy-web2.0 goodness.
posted by potch at 8:05 AM on January 10, 2007

Best answer: I second the recommendation to check out Behaviour. It "uses CSS selectors to apply Javascript behaviours".
posted by purephase at 8:11 AM on January 10, 2007

somefunction = function() { alert('it worked') };

That's all there is to it.
posted by icebourg at 8:40 AM on January 10, 2007

Best answer: After some digging in the DOM with Firebug, I found that if you have the name of a function in a String, then window[String] returns a reference to the function. Now that it's working, Here's a short little link to the code and examples and stuff. Thanks for the help everyone!
posted by potch at 8:45 AM on January 10, 2007

Typo?

	var linkElement = linkTags.item(i);
			var ajax = new Ajax.Request(linkElement["href"], {onComplete: ActionSheets_Parse});
		if (linkElement["rel"] == "JAS") {
		}

Shouldn't it be

	var linkElement = linkTags.item(i);
		if (linkElement["rel"] == "JAS") {
			var ajax = new Ajax.Request(linkElement["href"], {onComplete: ActionSheets_Parse});
		}

posted by Deathalicious at 9:19 AM on January 10, 2007

Response by poster: Deathalicious: yes, it should. Thanks!
posted by potch at 9:21 AM on January 10, 2007