Beware trailing comma in JavaScript prototypes

I spent more time than I care to admit tracking down this one, perhaps this post will save someone else the trouble...

When defining a number of functions in a prototype in JavaScript, do not include a trailing comma after the last function:

MyType.prototype = {
    foo : function() {
          // ...
    },

    bar : function() {
        //...
    }, //<- fails in IE!
 }

What was especially tricky about tracking this problem down was that FireFox works with or without the trailing comma, so it only fails in IE!

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Posted Jun 19 2007, 06:52 AM by fritz-onion