Q: I have an iframe calling page X, on page X is a div w/ id=test. The value of this test div is "bubbles". On the parent page I need to read the value of the div and store it as a javascript var.
Outcome: on the parent page have a document.write(iframedivvalue); output that will = whatever the value of the div inside the iframe.
Note:
- as of right now page X is on a different domain.
- I am NOT trying to set anything inside the iframe, just read a divs value.
You will still be blocked by the same-origin policy if the domains mismatch. Doesn't matter if you're just trying to grab a value.
As Alex says on the comment above, you will still be blocked by the JavaScript 'same-origin' policy.
If your iframe is on the same domain, then you could try this:
document.getElementById('iframe-id').contentDocument.getElementById('canvas');
Assuming the iFrame has an assigned ID:
var iframe_div = document.getElementById('iframeid').document.getElementById('mydiv');
var content = iframe_div.innerHTML;
I believe should work.
来源：https://stackoverflow.com/questions/5022464/getelementbyid-within-iframe