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jquery get height of iframe content when loaded

Posted by: admin November 19, 2017 Leave a comment

Questions:

I have a Help page, help.php that I am loading inside an iframe in main.php
How can I get the height of this page once it has loaded in the iframe?

I am asking this because I can’t style the height of to iframe to 100% or auto. That’s why I think I need to use javascript..
I am using jQuery

CSS:

body {
    margin: 0;
    padding: 0;
}
.container {
    width: 900px;
    height: 100%;
    margin: 0 auto;
    background: silver;
}
.help-div {
    display: none;
    width: 850px;
    height: 100%;
    position: absolute;
    top: 100px;
    background: orange;
}
#help-frame {
    width: 100%;
    height: auto;
    margin:0;
    padding:0;
}

JS:

$(document).ready(function () {
    $("a.open-help").click(function () {
        $(".help-div").show();
        return false;
    })
})

HTML:

<div class='container'>
    <!-- -->
    <div class='help-div'>
        <p>This is a div with an iframe loading the help page</p>
        <iframe id="help-frame" src="../help.php" width="100%" height="100%" frameborder="1"></iframe>
    </div>  <a class="open-help" href="#">open Help in iFrame</a>

    <p>hello world</p>
    <p>hello world</p>
    <p>hello world</p>
    <p>hello world</p>
    <p>hello world</p>
</div>
Answers:

ok I finally found a good solution:

$('iframe').load(function() {
    this.style.height =
    this.contentWindow.document.body.offsetHeight + 'px';
});

Because some browsers (older Safari and Opera) report onload completed before CSS renders you need to set a micro Timeout and blank out and reassign the iframe’s src.

$('iframe').load(function() {
    setTimeout(iResize, 50);
    // Safari and Opera need a kick-start.
    var iSource = document.getElementById('your-iframe-id').src;
    document.getElementById('your-iframe-id').src = '';
    document.getElementById('your-iframe-id').src = iSource;
});
function iResize() {
    document.getElementById('your-iframe-id').style.height = 
    document.getElementById('your-iframe-id').contentWindow.document.body.offsetHeight + 'px';
}

Questions:
Answers:

The less complicated answer is to use .contents() to get at the iframe. Interestingly, though, it returns a different value from what I get using the code in my original answer, due to the padding on the body, I believe.

$('iframe').contents().height() + 'is the height'

This is how I’ve done it for cross-domain communication, so I’m afraid it’s maybe unnecessarily complicated. First, I would put jQuery inside the iFrame’s document; this will consume more memory, but it shouldn’t increase load time as the script only needs to be loaded once.

Use the iFrame’s jQuery to measure the height of your iframe’s body as early as possible (onDOMReady) and then set the URL hash to that height. And in the parent document, add an onload event to the iFrame tag that will look at the location of the iframe and extract the value you need. Because onDOMReady will always occur before the document’s load event, you can be fairly certain the value will get communicated correctly without a race condition complicating things.

In other words:

…in Help.php:

var getDocumentHeight = function() {
    if (location.hash === '') { // EDIT: this should prevent the retriggering of onDOMReady
        location.hash = $('body').height(); 
        // at this point the document address will be something like help.php#1552
    }
};
$(getDocumentHeight);

…and in the parent document:

var getIFrameHeight = function() {
    var iFrame = $('iframe')[0]; // this will return the DOM element
    var strHash = iFrame.contentDocument.location.hash;
    alert(strHash); // will return something like '#1552'
};
$('iframe').bind('load', getIFrameHeight );

Questions:
Answers:

I found the following to work on Chrome, Firefox and IE11:

$('iframe').load(function () {
    $('iframe').height($('iframe').contents().height());
});

When the Iframes content is done loading the event will fire and it will set the IFrames height to that of its content. This will only work for pages within the same domain as that of the IFrame.

Questions:
Answers:

You don’t need jquery inside the iframe to do this, but I use it cause the code is so much simpler…

Put this in the document inside your iframe.

$(document).ready(function() {
  parent.set_size(this.body.offsetHeight + 5 + "px");  
});

added five above to eliminate scrollbar on small windows, it’s never perfect on size.

And this inside your parent document.

function set_size(ht)
{
$("#iframeId").css('height',ht);
}

Questions:
Answers:

The code to do this without jQuery is trivial nowadays:

const frame = document.querySelector('iframe')
function syncHeight() {
  this.style.height = `${this.contentWindow.document.body.offsetHeight}px`
}
frame.addEventListener('load', syncHeight)

To unhook the event:

frame.removeEventListener('load', syncHeight)

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