Set focus on control inside iFrame (jQuery)

//get the IFRAME element - note no hashes in the name, we're using browser functionality 
var iframeRef = document.getElementById("IFRAMEID"); 
//focus the IFRAME element 
$(iframeRef).focus(); 
//use JQuery to find the control in the IFRAME and set focus 
$(iframeRef).contents().find("#CONTROLID").focus();

Source

JavaScript: Parent -> Frame function calls

For this example I have 2 html pages:

Page1.html and Page2.html

If Page2 is shown as iframe inside Page1 and has this function:

<script type="text/javascript">

        function showMessage(m) {

            document.getElementById("message").innerHTML = m;

        }

</script>

Than it can be called from Page1 like this:

<script type="text/javascript">

    window.onload = function() {

        window.frames[0].showMessage("Hello from Main Page in iFrame");

    };    

</script>

 

Source