[javascript] jQuery iframe load() event?

Does anyone know if there is such a thing?

I have a iframe that's being inserted with $.ajax() and I want to do some stuff after the contents from the iframe are completely loaded:

....
 success: function(html){  // <-- html is the IFRAME (#theiframe)
          $(this).html(html);   // $(this) is the container element
          $(this).show();
          $('#theiframe').load(function(){
             alert('loaded!');
          } 
....

it works, but I see the IFRAME is loaded twice (the alert also shows twice).

You may use the jquery's Contents method to get the content of the iframe.

Without code in iframe + animate:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.0/jquery.min.js"></script>
<script language="javascript" type="text/javascript">

function resizeIframe(obj) {

    jQuery(document).ready(function($) {

        $(obj).animate({height: obj.contentWindow.document.body.scrollHeight + 'px'}, 500)

    });

}    
</script>
<iframe width="100%" src="iframe.html" height="0" frameborder="0" scrolling="no" onload="resizeIframe(this)" >

That's the same behavior I've seen: iframe's load() will fire first on an empty iframe, then the second time when your page is loaded.

Edit: Hmm, interesting. You could increment a counter in your event handler, and a) ignore the first load event, or b) ignore any duplicate load event.

use iframe onload event

$('#theiframe').on("load", function() {
    alert(1);
});

Along the lines of Tim Down's answer but leveraging jQuery (mentioned by the OP) and loosely coupling the containing page and the iframe, you could do the following:

In the iframe:

<script>
    $(function() {
        var w = window;
        if (w.frameElement != null
                && w.frameElement.nodeName === "IFRAME"
                && w.parent.jQuery) {
            w.parent.jQuery(w.parent.document).trigger('iframeready');
        }
    });
</script>

In the containing page:

<script>
    function myHandler() {
        alert('iframe (almost) loaded');
    }
    $(document).on('iframeready', myHandler);
</script>

The iframe fires an event on the (potentially existing) parent window's document - please beware that the parent document needs a jQuery instance of itself for this to work. Then, in the parent window you attach a handler to react to that event.

This solution has the advantage of not breaking when the containing page does not contain the expected load handler. More generally speaking, it shouldn't be the concern of the iframe to know its surrounding environment.

Please note, that we're leveraging the DOM ready event to fire the event - which should be suitable for most use cases. If it's not, simply attach the event trigger line to the window's load event like so:

$(window).on('load', function() { ... });

If you want it to be more generic and independent, you can use cookie. Iframe content can set a cookie. With jquery.cookie and a timer (or in this case javascript timer), you can check if the cookie is set each second or so.

//token should be a unique random value which is also sent to ifame to get set
iframeLoadCheckTimer = window.setInterval(function () {
        cookieValue = $.cookie('iframeToken');  
        if (cookieValue == token)
        {
            window.clearInterval(iframeLoadCheckTimer );
            $.cookie('iframeToken', null, {
                expires: 1, 
                path: '/'
         });
        }
 }, 1000);