How can I access the DOM elements within an iFrame

Now that you've changed the question into something different, you have to wait for an iframe window to load before you can access the content in it and you can't use jQuery's .ready() on a different document (it doesn't work on another document).

$(document).ready(function() {
    // get the iframe in my documnet
    var iframe = document.getElementById("testFrame");
    // get the window associated with that iframe
    var iWindow = iframe.contentWindow;

    // wait for the window to load before accessing the content
    iWindow.addEventListener("load", function() {
        // get the document from the window
        var doc = iframe.contentDocument || iframe.contentWindow.document;

        // find the target in the iframe content
        var target = doc.getElementById("target");
        target.innerHTML = "Found It!";
    });
});

Test page here.

---

EDIT: Upon further research, I found that jQuery will do some of this work for you like this and the jQuery solution appears to work in all the major browsers:

$(document).ready(function() {
    $("#testFrame").load(function() {
        var doc = this.contentDocument || this.contentWindow.document;
        var target = doc.getElementById("target");
        target.innerHTML = "Found It!";
    });
});

Test page here.

In looking at the jQuery implementation for this, all it is really doing is setting up a load event listener on the iFrame itself.

(...)

After a bunch more research and testing, here's a function that will tell you when an iFrame hits the DOMContentLoaded event rather than waiting for the load event (which can take longer with images and style sheets).

// This function ONLY works for iFrames of the same origin as their parent
function iFrameReady(iFrame, fn) {
    var timer;
    var fired = false;

    function ready() {
        if (!fired) {
            fired = true;
            clearTimeout(timer);
            fn.call(this);
        }
    }

    function readyState() {
        if (this.readyState === "complete") {
            ready.call(this);
        }
    }

    // cross platform event handler for compatibility with older IE versions
    function addEvent(elem, event, fn) {
        if (elem.addEventListener) {
            return elem.addEventListener(event, fn);
        } else {
            return elem.attachEvent("on" + event, function () {
                return fn.call(elem, window.event);
            });
        }
    }

    // use iFrame load as a backup - though the other events should occur first
    addEvent(iFrame, "load", function () {
        ready.call(iFrame.contentDocument || iFrame.contentWindow.document);
    });

    function checkLoaded() {
        var doc = iFrame.contentDocument || iFrame.contentWindow.document;
        // We can tell if there is a dummy document installed because the dummy document
        // will have an URL that starts with "about:".  The real document will not have that URL
        if (doc.URL.indexOf("about:") !== 0) {
            if (doc.readyState === "complete") {
                ready.call(doc);
            } else {
                // set event listener for DOMContentLoaded on the new document
                addEvent(doc, "DOMContentLoaded", ready);
                addEvent(doc, "readystatechange", readyState);
            }
        } else {
            // still same old original document, so keep looking for content or new document
            timer = setTimeout(checkLoaded, 1);
        }
    }
    checkLoaded();
}

This is simply called like this:

// call this when you know the iFrame has been loaded
// in jQuery, you would put this in a $(document).ready()
iFrameReady(document.getElementById("testFrame"), function() {
    var target = this.getElementById("target");
    target.innerHTML = "Found It!";
});

https://stackoverflow.com/questions/24603580/how-can-i-access-the-dom-elements-within-an-iframe/24603642#comment38157462_24603642