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Open Iframe Resizer

API

initialize

Called to automatically track iframes and resize the selected iframes when their inner content changes.

settings : A settings object for the selected iframes. Default settings will be applied if the settings object is empty.

selector : The string selector for the iframe(s) or the HTMLIFrameElement to be resized. If empty, all iframe elements in the document will be selected.

It returns a Promise of an array of objects, which can be used to stop tracking an iframe.

Example 1

// Track a specific iframe using its ID and customizing certain properties
initialize({
  bodyPadding: "0px",
  bodyMargin: "0px"
}, "#my-iframe");

Example 2

async function initializeAllIframes() {
  const results = await initialize(); // Track all existing iframes with default settings
  results.forEach(result => result.unsubscribe());  // You can later untrack these iframes
}

Settings

Below is a detailed description of each property:

offsetSize

  • Type: number
  • Description: Offset added to the calculated resize size (in pixels).
  • Default: 0

checkOrigin

  • Type: string[] | boolean
  • Description: Specifies whether to check the origin of incoming messages.
    • Accepts an array of allowed origins or a boolean.
    • If true, incoming messages are allowed from the origins of the registered iframes.
  • Default: true

enableLegacyLibSupport

  • Type: boolean
  • Description: Allows the library to communicate with a cross-origin child iframe containing the original “iframe-resizer” script. Useful if you do not control the child domain.
  • Default: false

targetElementSelector

  • Type: string | undefined
  • Description: By default, the root element observed for resizing is the <html> document. In more complex layouts, the scrolling container may be elsewhere. This setting allows you to customize the root element that should be observed for resize events.
  • Default: undefined

bodyPadding

  • Type: string | undefined
  • Description: Customize the padding style of the iframe body.
  • Default: undefined

bodyMargin

  • Type: string | undefined
  • Description: Customize the margin style of the iframe body.
  • Default: undefined

onIframeResize

  • Type: (context: ResizeContext) => void
  • Description: Listener that is called after the iframe has been resized. You can use a predefined handler like updateParentScrollOnResize create your own custom handler.
  • Default: undefined

onBeforeIframeResize

  • Type: (context: BeforeResizeContext) => boolean | undefined
  • Description: Called whenever the observed content size changes and the iframe is about to be resized. Return false to cancel the resize; returning true or nothing will allow it.
  • Default: undefined

Resize handlers

updateParentScrollOnResize

This handler attempts to fix the issue where the iframe is resized after interaction. For example, if your iframe contains a multi-step form where each step has a different height, the iframe might disappear from view after resizing.

If the iframe is focused, this handler will maintain the iframe’s position in the viewport after a resize by scrolling.

initialize({ onIframeResize: updateParentScrollOnResize }, "#myIframe");