How do I target the search bar from a Firefox extension?

I'm new to building extensions -- and would like some help with knowing how to target the standard Google search bar that comes with Firefox..

I am thinking I have to find o开发者_运维问答ut which meni ID it is and assign it somehow within the .xul file..

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From chrome (normally overlay of the chrome://browser/content/browser.xul) you can get access to search bar by getting it with document.getElementById('searchbar') The best way to find ids you need is by using Dom Inspector: https://addons.mozilla.org/en-US/firefox/addon/dom-inspector-6622/

Anyhow, if you want to access inner dom elements of the searchbar you'll need to use getAnonymousElementByAttribute because that's anonymous content (from XBL binding). So if you need to get input element itself (where you're typing your search terms) you'll do it something like this from chrome:

var searchbarElement = document.getElementById('searchbar');
var input = document.getAnonymousElementByAttribute(searchbarElement, 'anonid', 'input');

You'll need to use Dom Inspector to figure out which element you need and how to access it.