Q:

Chrome-Extension: iterate through all tabs?

How would I iterate through all tabs a user has open and then check if they have a particular HTML item with id = 'item'?

A:

It appears this method has been deprecated in favor of chrome.tabs.query:
http://developer.chrome.com/extensions/tabs.html#method-query
So now you'd want to do:
chrome.tabs.query({}, function(tabs) { /* blah */ } );

Passing an empty queryInfo parameter would return all of the tabs.

A:

You can make it like this :
chrome.tabs.getAllInWindow(null, function(tabs){
    for (var i = 0; i < tabs.length; i++) {
    chrome.tabs.sendRequest(tabs[i].id, { action: "xxx" });                         
    }
});

After that to look after your item, if you can make it like this :
document.getElementById('item')

Don't forget that you can't manipulate the HTML by using the "background page" So the first code snip is for the background page, and the second have to be on a content script ;)

