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iframe-resizer - Keep same and cross domain iFrames sized to their content with support for window/content resizing, and multiple iFrames.

Created 5 years ago   Views 7693   downloads 1248    Author davidjbradshaw
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iFrame Resizer

This library enables the automatic resizing of the height and width of both same and cross domain iFrames to fit the contained content. It uses postMessage to pass messages between the host page and the iFrame and when available MutationObserver to detect DOM changes, with a fallback to setInterval for IE8-10.

The code also detects browser events that can cause the content to resize; provides functions to allow the iFrame to set a custom size and close itself. Plus it supports having multiple iFrames on the host-page and additionally provides for the sending of simple messages from the iFrame to the parent page.

For security, by default the host-page automatically checks that the origin of incoming messages are from the domain of the page listed in the src property of the iFrame.

The package contains two minified JavaScript files in the js folder. The first (iframeResizer.min.js) is for the page hosting the iFrames. It can be called with native JavaScript;

iFrameResize( [{options}], [css selector] || [iframe] );

or via jQuery. (See notes below for using native version with IE8).

$('iframe').iFrameResize( [{options}] );

The second file (iframeResizer.contentWindow.min.js) is a native JavaScript file that needs placing in the page contained within your iFrame. This file is designed to be a guest on someone else's system, so has no dependancies and won't do anything until it's activated by a message from the containing page.

The normal configuration is to have the iFrame resize when the browser window changes size or the content of the iFrame changes. To set this up you need to configure one of the dimensions of the iFrame to a percentage and tell the library only to update the other dimension. Normally you would set the width to 100% and have the height scale to fit the content.

<iframe src="" 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. If you have problems, check the troubleshooting section below.

###Example To see this working take a look at this example and watch the console.

default: false
type:    boolean

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.

default: true
type:    boolean

When enabled changes to the Window size or the DOM will cause the iFrame to resize to the new content size. Disable if using size method with custom dimensions.

default: null
type:    string 

Override the body background style in the iFrame.

default: null
type:    string || number

Override the default body margin style in the iFrame. A string can be any valid value for the CSS margin attribute, for example '8px 3em'. A number value is converted into px.

default: true
type:    boolean

When set to true, only allow incoming messages from the domain listed in the src property of the iFrame tag. If your iFrame navigates between different domains, ports or protocols; then you will need to disable this option.

default: false
type:    boolean

If enabled, a window.parentIFrame object is created in the iFrame that contains methods outlined below.

default: 32  (in ms)
type:    number

In browsers that don't support mutationObserver, such as IE10, the library falls back to using setInterval, to check for changes to the page size. The default value is equal to two frame refreshes at 60Hz, setting this to a higher value will make screen redraws noticeable to the user.

Setting this property to a negative number will force the interval check to run instead of mutationObserver.

Set to zero to disable.

default: 'bodyOffset'
values:  'bodyOffset' | 'bodyScroll' | 'documentElementOffset' | 'documentElementScroll' | 
         'max' | 'min' | 'grow' | 'lowestElement'

By default the height of the iFrame is calculated by converting the margin of the body to px and then adding the top and bottom figures to the offsetHeight of the body tag.

In cases where CSS styles causes the content to flow outside the body you may need to change this setting to one of the following options. Each can give different values depending on how CSS is used in the page and each has varying side-effects. You will need to experiment to see which is best for any particular circumstance.

  • bodyScroll uses document.body.scrollHeight
  • documentElementOffset uses document.documentElement.offsetHeight
  • documentElementScroll uses document.documentElement.scrollHeight
  • max takes the largest value of the main four options
  • min takes the smallest value of the main four options
  • grow same as max but disables the double resize that is used to workout if the iFrame needs to shrink. This provides much better performance if your iFrame will only ever increase in size
  • lowestElement Loops though every element in the the DOM and finds the lowest bottom point.


The bodyScroll, documentElementScroll, max and min options can cause screen flicker and will prevent the interval trigger downsizing the iFrame when the content shrinks. This is mainly an issue in IE 10 and below, where the mutationObserver event is not supported. To overcome this you need to manually trigger a page resize by calling the parentIFrame.size() method when you remove content from the page.

The lowestElement option is the most reliable way of determining the page height. However, it does have a performance impact in older versions of IE. In one screen refresh (16ms) Chrome 34 can calculate the position of around 10,000 html nodes, whereas IE 8 can calculate approximately 50. It is recommend to fallback to max or grow in IE10 and below.

default: infinity
type:    integer

Set maximum height/width of iFrame.

default: 0
type:    integer

Set minimum height/width of iFrame.

default: false
type:    boolean

Enable scroll bars in iFrame.

default: true
type:    boolean

Resize iFrame to content height.

default: false
type:    boolean

Resize iFrame to content width.

default: 0
type:    integer

Set the number of pixels the iFrame content size has to change by, before triggering resize of the iFrame.

type: function (iframeID)

Called when iFrame is closed via parentIFrame.close() method.

type: function (iframe)

Initial setup callback function.

type: function ({iframe,message})

Receive message posted from iFrame with the parentIFrame.sendMessage() method.

type: function ({iframe,height,width,type})

Function called after iFrame resized. Passes in messageData object containing the iFrame, height, width and the type of event that triggered the iFrame to resize.

type: function ({x,y})

Called before the page is repositioned after a request from the iFrame, due to ethier an in page link, or a direct request from either parentIFrame.scrollTo() or parentIFrame.scrollToOffset(). If this callback function returns false, it will stop the library from repositioning the page, so that you can implement your own animatied page scrolling instead.

To enable these methods you must set enablePublicMethods to true. This creates the window.parentIFrame object in the iFrame. These method should be contained by a test for the window.parentIFrame object, in case the page is not loaded inside an iFrame. For example:

if ('parentIFrame' in window) {

Remove the iFrame from the parent page.

Returns the ID of the iFrame that the page is contained in.

Scroll the parent page to the coordinates x and y.

Scroll the parent page to the coordinates x and y relative to the position of the iFrame.

Send data to the containing page, message can be any data type that can be serialized into JSON. The targetOrigin option is used to restrict where the message is sent to; to stop an attacker mimicking your parent page. See the MDN documentation on postMessage for more details.

Change the method use to workout the height of the iFrame.

Manually force iFrame to resize. This method optionally accepts two arguments: customHeight & customWidth. To use them you need first to disable the autoResize option to prevent auto resizing and enable the sizeWidth option if you wish to set the width.

    autoResize: false,
    enablePublicMethods: true,
    sizeWidth: true

Then you can call the size method with dimensions:

if ('parentIFrame' in window) {
    parentIFrame.size(100); // Set height to 100px 


The first step to investigate a problem is to enable the log option and then open the JavaScript Console. This will enable you to see what both the iFrame and host page are up to and also see any JavaScript error messages.

Solutions for the most common problems are outlined in this section.

If a larger element of content is removed from the normal document flow, through the use of absolute positioning, it can prevent the browser working out the correct size of the page. In such cases you can change the heightCalculationMethod to uses one of the other sizing methods, normally you will be best off selecting the max or lowestElement options to avoid cross browser differences.

The most likely cause of this problem is having set the height of an element to be 100% of the page somewhere in your CSS. This is normally on the html or body elements, but it could be on any element in the page.

Not having a valid HTML document type in the iFrame can also sometimes prevent downsizing. At it's most simplest this can be the following.

<!DOCTYPE html>

###IFrame not resizing The most common cause of this is not placing the iframeResizer.contentWindow.min.js script inside the iFramed page. If the other page is on a domain outside your control and you can not add JavaScript to that page, then now is the time to give up all hope of ever getting the iFrame to size to the content. As it is impossible to work out the size of the contained page, without using JavaScript on both the parent and child pages.

###IFrame not detecting CSS :hover events If your page resizes via CSS :hover events, these won't be detect by default. It is however possible to create mouseover and mouseout event listeners on the elements that are resized via CSS and have these events call the parentIFrame.size() method. With jQuery this can be done as follows, once you have set the enablePublicMethods option to true.

function resize(){
    if ('parentIFrame' in window) {
        setTimeout(function(){ // Fix FireFox timing issue 
$(*Element with hover style*).hover(resize);

To call methods in the iFrame, you need to set the enablePublicMethods option to true.

It is not possible to add the required JavaScript to PDF and ODF files. However, you can get around this limitation by using ViewerJS to render these files inside a HTML page, that also contains the iFrame JavaScript file (iframeResizer.contentWindow.min.js).

By default the origin of incoming messages is checked against the src attribute of the iFrame. If they don't match an error is thrown. This behaviour can be disabled by setting the checkOrigin option to false.

###jQuery version

Works with all browsers which support window.postMessage (IE8+).

###Native version

Additionally requires support for Array.prototype.forEach (IE9+) and document.querySelectorAll (IE8 Standards Mode). For IE8 force Standards Mode,

<meta http-equiv="X-UA-Compatible" content="IE=edge">

and use the MDN PolyFill on the host page.

if (!Array.prototype.forEach){
    Array.prototype.forEach = function(fun /*thisArg */){
        "use strict";
        if (this === void 0 || this === null || typeof fun !== "function") throw new TypeError();
            t = Object(this),
            len = t.length >>> 0,
            thisArg = arguments.length >= 2 ? arguments[1] : void 0;
        for (var i = 0; i < len; i++)
            if (in t)
      , t[i], i, t);

In lieu of a formal style-guide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using Grunt.

##Version History

  • v2.8.3 Throw error if passed a non-DOM object.
  • v2.8.2 #145 Fixed in page links, to work with HTML IDs that are not valid CSS IDs [Erin Millard]. Moved map files from src to js folder. Added to NPM.
  • v2.8.1 #138 Added option to pass in iFrame object, instead of selector.
  • v2.8.0 #68 Added support for in page links and scrollCallback() function. #140 Added listener for transitionend event [Mat Brown]. Added listeners for animation events. Added listener for deviceorientation event. Improved logging for nested iFrames.
  • v2.7.1 #131 Fix code that works out position of iFrame on host page.
  • v2.7.0 #129 Parse data passed to parentIFrame.sendMessage() into JSON to allow complex data types to be sent to messageCallback().
  • v2.6.5 #107 Added Node support for use with Browserify.
  • v2.6.4 #115 Added parentIFrame.scrollToOffset() method.
  • v2.6.3 #115 Fixed issue with the range check sometimes causing non-resizing messages to be rejected.
  • v2.6.2 #104 Fixed issue with jQuery.noConflict [Dmitry Mukhutdinov].
  • v2.6.1 #91 Fixed issue with jQuery version requiring empty object if no options are being set.
  • v2.6.0 Added parentIFrame.scrollTo() method. Added Tolerance option. #85 Update troubleshooting guide [Kevin Sproles].
  • v2.5.2 #67 Allow lowercase <iframe> tags for XHTML complience [SlimerDude]. #69 Fix watch task typo in gruntfile.js [Matthew Hupman]. Remove trailing comma in heightCalcMethods array #76 [Fabio Scala].
  • v2.5.1 #58 Fixed endless loop and margin issues with an unnested mid-tier iframe. #59 Fixed main property of Bower config file.
  • v2.5.0 Added minHeight, maxHeight, minWidth and maxWidth options. Added initCallback and closedCallback functions (Close event calling resizedCallback is deprecated). Added grow and lowestElement heightCalculationMethods. Added AMD support. #52 Added sendMessage example. #54 Work around IE8's borked JS execution stack. #55 Check datatype of passed in options.
  • v2.4.8 Fix issue when message passed to messageCallback contains a colon.
  • v2.4.7 #49 Deconflict requestAnimationFrame.
  • v2.4.6 #46 Fix iFrame event listener in IE8.
  • v2.4.5 #41 Prevent error in FireFox when body is hidden by CSS [Scott Otis].
  • v2.4.4 Enable nested iFrames (#31 Filter incoming iFrame message in host-page script. #33 Squash unexpected message warning when using nested iFrames. Improved logging for nested iFrames). #38 Detect late image loads that cause a resize due to async image loading in WebKit [Yassin]. Fixed :Hover example in FireFox. Increased trigger timeout lock to 64ms.
  • v2.4.3 Simplified handling of double fired events. Fixed test coverage.
  • v2.4.2 Fix missing 'px' unit when resetting height.
  • v2.4.1 Fix screen flicker issue with scroll height calculation methods in v2.4.0.
  • v2.4.0 Improved handling of alternate sizing methods, so that they will now shrink on all trigger events, except Interval. Prevent error when incoming message to iFrame is an object.
  • v2.3.2 Fix backwards compatibility issue between V2 iFrame and V1 host-page scripts.
  • v2.3.1 Added setHeightCalculationMethod() method in iFrame. Added min option to the height calculation methods. Invalid value for heightCalculationMethod is now a warning rather than an error and now falls back to the default value.
  • v2.3.0 Added extra heightCalculationMethod options. Inject clearFix into 'body' to work around CSS floats preventing the height being correctly calculated. Added meaningful error message for non-valid values in heightCalculationMethod. Stop click events firing for 50ms after size events. Fixed hover example in old IE.
  • v2.2.3 #26 Locally scope jQuery to $, so there is no dependancy on it being defined globally.
  • v2.2.2 #25 Added click listener to Window, to detect CSS checkbox resize events.
  • v2.2.1 #24 Prevent error when incoming message to host page is an object [Torjus Eidet].
  • v2.2.0 Added targetOrigin option to sendMessage function. Added bodyBackground option. Expanded troubleshooting section.
  • v2.1.1 #16 Option to change the height calculation method in the iFrame from offsetHeight to scrollHeight. Troubleshooting section added to docs.
  • v2.1.0 Added sendMessage() and getId() to window.parentIFrame. Changed width calculation to use scrollWidth. Removed deprecated object name in iFrame.
  • v2.0.0 Added native JS public function, renamed script filename to reflect that jQuery is now optional. Renamed do(Heigh/Width) to size(Height/Width), renamed contentWindowBodyMargin to bodyMargin and renamed callback resizedCallback. Improved logging messages. Stop resize event firing for 50ms after interval event. Added multiple page example. Workout unsized margins inside the iFrame. The bodyMargin property now accepts any valid value for a CSS margin. Check message origin is iFrame. Removed deprecated methods.
  • v1.4.4 Fixed bodyMargin bug.
  • v1.4.3 CodeCoverage fixes. Documentation improvements.
  • v1.4.2 Fixed size(250) example in IE8.
  • v1.4.1 Setting interval to a negative number now forces the interval test to run instead of MutationObserver.
  • v1.4.0 #12 Option to enable scrolling in iFrame, off by default. #13 Bower dependancies updated.
  • v1.3.7 Stop resize event firing for 50ms after size event. Added size(250) to example.
  • v1.3.6 #11 Updated jQuery to v1.11.0 in example due to IE11 having issues with jQuery v1.10.1.
  • v1.3.5 Documentation improvements. Added Grunt-Bump to build script.
  • v1.3.0 IFrame code now uses default values if called with an old version of the host page script. Improved function naming. Old names have been deprecated and removed from docs.
  • v1.2.5 Fix publish to
  • v1.2.0 Added autoResize option, added height/width values to iFrame public size function, set HTML tag height to auto, improved documentation [All Jure Mav]. Plus setInterval now only runs in browsers that don't support MutationObserver and is on by default, sourceMaps added and close() method introduced to parentIFrame object in iFrame.
  • v1.1.1 Added event type to messageData object.
  • v1.1.0 Added DOM MutationObserver trigger to better detect content changes in iFrame, #7 Set height of iFrame body element to auto to prevent resizing loop, if it's set to a percentage.
  • v1.0.3 #6 Force incoming messages to string. Migrated to Grunt 4.x. Published to Bower.
  • v1.0.2 #2 mime-type changed for IE8-10.
  • v1.0.0 Initial published release.

Copyright © 2013-14 David J. Bradshaw. Licensed under the MIT license.