Submitting a form in an iframe with JavaScript

Submit the Iframe's URL from javascript

   if (window.parent.$("#IframeId").length > 0) {
        window.parent.$("#IframeId")[0].contentDocument.forms[0].submit();
    }

Try this:

var MyIFrame = document.getElementById("myframe");
var MyIFrameDoc = (MyIFrame.contentWindow || MyIFrame.contentDocument);
if (MyIFrameDoc.document) MyIFrameDoc = MyIFrameDoc.document;
MyIFrameDoc.getElementById("myform").submit();

UPDATE

I can't figure out why this doesn't work, but here is something that does:

MyIFrameDoc.getElementById("mybutton").click();

iframe.php:

<input type="submit" name="submit" value="submit" id="mybutton" />

UPDATE 2

The reason you're getting the submit is not a function error is because you've named your submit button submit, so MyIFrameDoc.getElementById("myform").submit actually references an HTMLInputElement, not the HTMLFormElement.submit() method.

All you need to do is rename your submit button, e.g.:

<input type="submit" name="submit2" value="submit" />