Bookmark doesn't work on Mozilla, but does in Chrome

These are the steps that I recommend for creating bookmarklets:

1. Put everything in a function called immediately

You can use (function(){YOUR CODE}());or(function(){YOUR CODE})();

2. Collapse your code

You can use the online javascript script

3. URL-encode it

You can use an online encoder

In your case, it might be something like this:

(function(){m=document.getElementById('xxx');m.value=17}());

encoded as:

(function()%7Bm%3Ddocument.getElementById('xxx')%3Bm.value%3D17%7D())%3B

See DEMO .