miscoded

I've seen a particular mistake several times recently. It is a subtle ECMAScript spec violation that uncovers what browser engine was used during script development and testing: only Gecko-based browsers such as FireFox and presumably Mozilla allow it.

The error is to add a final comma inside an ECMAScript object literal:

var myObject = { property:'value' , }

Last seen in here and in an ad-hoc Chinese IME JavaScript demo (!) which I can't re-locate at the moment.

Try it out with the following bookmarklet:

javascript:try{eval("var a={a:'a',};");alert('Wrong behaviour!')}catch(e){alert('Correct behaviour!')}

A first-class example of how a minor browser sloppiness creates a serious compatibility problem.