README.md

Cross domain iframe resizer

This is a simple plugin to enable the resizing of cross domain iframes to fit the contained content. This package contains two minified JavaScript files in the js folder. The first (jquery.iframeResizer.min.js) is a jQuery plugin for the page hosting the iframe and the second one (iframeResizer.contentWindow.min.js) is a plain self contained JavaScript file that needs placing in the page contained within your iframe.

This plugin is built using the window.postMessage API to pass messages between the host page and the iframe. To see this working take a look at the example and watch the console log.

The code supports resizing the iframe when the browser window changes size or the content of the iframe changes. For this to work you need to set one of the dimensions to a percentage and tell the plugin only to update the other dimension. Normally you would set the width to 100% and have the height scale to fit the content. To set the plugin up for this create a basic iframe tag with the following options.

<iframe src="http://anotherdomain.com/frame.content.html" width="100%" scrolling="no"></iframe>

Note that scrolling is set to 'no', as older versions of IE don't allow this to be turned off in code and can just slightly add a bit of extra space to the bottom of the content that it doesn't report when it returns the height.

Next we initialise the plugin on the host page. This example shows all the default options and the values returned to the callback function.

$('iframe').iFrameSizer({
			log: false,
			contentWindowBodyMargin:8,
			doHeight:true,
			doWidth:false,
			enablePublicMethods:false,
			interval:0,
			callback:function(messageData){
				$('p#callback').html('<b>Frame ID:</b> ' + messageData.iframe.id + 
									' <b>Height:</b> ' + messageData.height + 
									' <b>Width:</b> ' + messageData.width);
			}
		});

The contentWindowBodyMagin setting is used to override the default browser body tag style. As we can not reliably read this value and it's not included in the figure returned by document.body.offsetHeight. So the only way we can work this out is to set it, 8px is the default option in firefox. However, you will most likely want to set this to zero so that the content of you iframe is at the edge of the iframe.

Setting the log option to true will make the scripts in both the host page and the iframe output everything they do to the JavaScript console so you can see the communication between the two scripts.

###Dynamic content in iframe

In most browsers the resize event only fires when the browser window resizes. This means that dynamic changes to the document that change the size of the content don't trigger any events. To overcome this limitation this plugin offers two options that can be set to enable functions in the iFrame.

The preferred option is to set enablePublicMethods to true. This creates a window.iFrameResizer object in the browser. Then whenever the content is changed in the iFrame you can call the window.iFrameSizer.trigger() method to have the iFrame resize to the new content. This should be wrapped in a test for the method to avoid errors when the page is not run in an iFrame.

if (window.iFrameSizer && window.iFrameSizer.trigger) {
	window.iFrameSizer.trigger();
}

As a secondary option in cases where it is not possible to modify the existing JavaScript you can set an interval timer in the iframe to check changes to the content. This is done by setting the interval option to a numeric value other than zero, the suggested value is 32, which causes the check to run every other screen refresh. Higher values lead to the screen redraw becoming noticeable to the user.

NOTE: Not all browsers allow the postmessage API to work with locally hosted files.