I have two documents, one of which is embedded into the other with an iframe. I'm trying to use this code to access the img tag inside the iframe, however, I cannot use the document.getElementById function on the iframe element:

iframes = document.getElementsByTagName("iframe")
spaces = iframes[0].contentWindow.document;
spaces = spaces.getElementsByTagName("img")
for (var i=0, max=spaces.length; i < max; i++) {
     alert(spaces[i].innerHTML)
}
alert(spaces)
var x = document.getElementById("frame");
var y = (x.contentWindow || x.contentDocument);
if (y.document)y = y.document;
alert(y.body.innerHTML)

spaces returns [object HTMLCollection] and y returns [object HTMLDocument]