JQuery to check for duplicate ids in a DOM

Question

I'm writing applications with ASP.NET MVC. In contrast to traditional ASP.NET you're a lot more responsible for creating all the ids in your generated page. ASP.NET would give you nasty, but unique ids.

I'd like to add a quick little jQuery script to check my document for duplicate ids. They may be ids for DIVS, images, checkboxes, buttons etc.

<div id="pnlMain"> My main panel </div>
<div id="pnlMain"> Oops we accidentally used the same ID </div> 

I'm looking for a set and forget type utility that'll just warn me when I do something careless.

Yes i'd be using this only during testing, and alternatives (such as firebug plugins) are welcome too.

Answer 1

The following will log a warning to the console:

// Warning Duplicate IDs
$('[id]').each(function(){
  var ids = $('[id="'+this.id+'"]');
  if(ids.length>1 && ids[0]==this)
    console.warn('Multiple IDs #'+this.id);
});