"getElementById not a function" when trying to parse an AJAX response?

Question

I'm running GM_xmlhttpRequest (in a Greasemonkey script) and storing the responseText into a newly created HTML element:

var responseHTML = document.createElement('HTML');
...
onload: function() { responseHTML.innerHTML = response.responseText; }

And then I am trying to find an element in responseHTML:

console.log(responseHTML.getElementsByTagName('div'));
console.log(responseHTML.getElementById('result_0'));

The first works fine, but not the second. Any ideas?

Answer 1

getElementById is not a method of HTML elements. It is a method of the document node. As such you can't do:

div.getElementById('foo'); // invalid code

You can implement your own function to search the DOM by recursively going through children. On newer browsers you can even use the querySelector method. For minimal development you can use libraries like jQuery or sizzle.js (the query engine behind jQuery).