Why am I getting a TypeError when trying to call a function in an iFrame from the parent page?

I have a page (parent) with an iFrame (child) embedded in it, the iFrame contains a javascript function that I need to call from the parent. The page are on different domains, I don't know if that's the issue th开发者_Go百科ough. This is my code on the parent page:

<script type="text/javascript">
    function SaveChanges() {
        var iFrame = document.getElementById("iframeSite");
        iFrame.contentWindow.ExecuteSave();
    }
</script>

...and my code on the child page:

<script type="text/javascript">
    function ExecuteSave() {
        alert("test1");
    }
</script>

When I call "SaveChanges" in the parent it errors at the line where it attempts to call "ExecuteSave".

Uncaught TypeError: Property 'ExecuteSave' of object [object DOMWindow] 
is not a function

I've tried pretty much every variation of calling a child iFrame's function but still receive the same error.

Because the iframes are in different domains, you won't be able to directly call between them. This would be a violation of the Same Origin Policy.

There is a sanctioned way for having an iframe and a parent communicate. It's called postMessage().

Hope this helps!