Skip to content

Upgrading to Version 5

Version 5 of iframe-resizer drops support for legacy browsers and changes the way content resize events are detected. These changes greatly improves detection of content changes and iframe-resizer can now detect a number of events, such as user <textarea> resizing and CSS animation that previous versions struggled with.

These changes, along with further code optimizations, have lead to a large improvement in the performance of this library and it is now possible to have iframe-resizer both detect and keep up with CSS animations that causes the iframe to resize on every animation frame.

In addition to this, iframe-resizer 5 contains a number of other improvements and minor API changes that are detailed in this guide.

New NPM Packages

The main change has been to split the single package that contained both the parent and child JavaScript files into two separate packages, called @iframe-resizer/parent and @iframe-resizer/child. The jQuery plugin has also been split out into @iframe-resizer/jquery and the React version renamed to @iframe-resizer/react.

These new packages are designed to be drop in replacements for the previous version and in most situations will work without further code changes. Where the API has changed, the deprecated feature will trigger a waring in the browser console with advise on how to update your code.

API Changes

Over the last decade iframe-resizer has had a gradual increase in the number of available configuration options. With iframe-resizer 5 the aim has been to reduce and clarify these options in order to reduce complexity of using this library. The library will now auto detect a number of settings and also log advisory warnings to the console where it thinks you should make changes to the config.

Auto detection of the best content size calculation method

The previous versions of iframe-resizer offered the choice of a wide range of ways to calculate the size of the content in the iframe and it was left to the developer to determine which was the most appropriate by setting the heightCalculationMethod or widthCalculationMethod options.

With iframe-resizer 5, these options have been deprecated and iframe-resizer will now inspect the the page layout to automatically determine which is the best page size calculation method every time the iframe is resized. If it is determined that the best calculation method is taggedElement and the page has no tags, an advisory warning will be logged in the console to suggest adding these.

The name of the tag attributes have now been consolidated from data-iframe-height and data-iframe-width, to the single tag data-iframe-size.

Use of the old calculation options or the old tag names will trigger a deprecation warning in the console with advice on how to update your config.

New direction option replaces sizeHeight / sizeWidth and autoResize

This library has always supported resizing in both directions, but changing the direction confusingly required the setting of multiple different options in the config. This has now been consolidated into the new single direction option, which can have the following values: vertical, horizontal or none.

Use of the old values will trigger a deprecation warning.

New offset option

This new option allow you to adjust the value returned by the iframe for the dimension you are resizing, it can have either a positive or negative value.

New getParentProps() method replaces getPageInfo()

The getPageInfo() method as been deprecated in favor of the new getParentProps() method. Since it was first added to iframe-resizer getPageInfo has been extended and extended and become a mishmash of properties from the parent page DOM.

The new getParentProps method now groups values into three objects that contain information about the containing iframe tag, the parent document object, and the parent viewport.

// iframe.getBoundingRect()
iframe: {
// from document.documentElement
document: {
// window.visualViewport
viewport: {

Use of the old method will trigger a deprecation warning in the console.

The onInit() method has been renamed to onReady()

The onInit() method in the Parent Page API has been deprecated in favour of onReady(). This brings the parent page and iframe names for this event inline with each other.

Use of onInit() will trigger a deprecation warning in the console.

The size() method has been renamed to resize()

The size() method in the Child Page API has been deprecated in favour of resize(). This brings the child page name in line with the Parent Page API.

Use of size() will trigger a deprecation warning in the console.

Fixed bug where height/width were returned as strings

The onResized(), onMouseEnter() and onMouseLeave() events were returning height/width as a strings, this has now been fixed to return numbers.

The minHeight, minWidth, maxHeight and minWidth options have been removed

These settings are no longer required, as all target browsers now support setting these on the iframe via CSS.

Other Improvements

In addition to the above API changes, iframe-resizer 5 includes the following other enhancements.

Direct communication for same domain iframes

Iframe-resizer now detects when the iframe is on the same domain as the parent page, and will then pass messages directly via the browser DOM. This provides an additional performance improvement over always using postMessage(), which is now only used for cross-domain iframes.

Improved content resize detection

Dropping support for legacy browsers, has allowed version 5 to use the latest browser APIs to detect content changes, this greatly improves both performance and event detection, whilst also eliminating the issue of one changing being picked up by multiple different browser events.

Visibility checking

The visibility of both the iframe and the parent page are now observed, using the Page Visibility API. This allows resizing to be disabled while the iframe is not visible to the user.

Ensures CSS sizing of iframe html and body tags set to auto

The most common reason for Iframe Resizer to have difficulty resizing, or going into an endless loop of resizing, is the <html> and/or <body> elements having a size set on them by CSS. Iframe Resizer now inspects these elements and ensures that the height and width is set to auto.

TypeScript Types

TypeScript Types are now included in the NPM modules for the Parent, Child and React packages.

Was this page useful?