Jacob Paris

iframe.js

Last updated October 1, 2021 by Jacob Paris

This is a helper script to allow an embedded iframe to communicate with its parent page.

Place this on the page that contains the <iframe

The script

  • Listens for triggers emitted by application
  • Triggers scrolling on parent page
  • Triggers positions and resize iframe to fit content
  • Triggers opening of new pages
  • Passes UTM codes into iframe via URL query
jsiframe.js
1;(function (frameId) {
2  let connected = false
3
4  if (document.readyState === 'loading') {
5    document.addEventListener('readystatechange', addEventListenersToDocument)
6  } else {
7    addEventListenersToDocument()
8  }
9
10  function addEventListenersToDocument() {
11    if (connected) return
12
13    // The iframe with the funnel must have the following ID
14    const portal = document.getElementById(frameId)
15
16    // Set initial height to reduce jarring size changes
17    portal.style['min-height'] = '100vh'
18
19    window.addEventListener('message', function (e) {
20      // Resize iframe to fit contents
21      if (e.data.type && e.data.type === 'size') {
22        portal.style['min-height'] = e.data.height + 'px'
23      }
24
25      // Scroll parent page to top
26      if (e.data.type && e.data.type === 'scrolltop') {
27        document.body.scrollIntoView(e.data.options)
28      }
29
30      // Scroll parent page by X (Up, Down, Left or Right)
31      if (e.data.type && e.data.type === 'scrollby') {
32        // Make movements better on mobile
33        e.data.options.top =
34          window.innerHeight < e.data.options.top
35            ? window.innerHeight / 3
36            : e.data.options.top / 2
37        // Need to check to see if the browser supports smooth scroll
38        // otherwise use legacy scroll
39        if ('scrollBehavior' in document.documentElement.style) {
40          window.scrollBy(e.data.options)
41        } else {
42          window.scrollBy(e.data.options.left, e.data.options.top)
43        }
44      }
45
46      // Click link inside of iframe
47      if (e.data.type && e.data.type === 'link') {
48        window.open('./' + e.data.path.replace(new RegExp('^/'), ''), '_blank')
49      }
50    })
51
52    // Extract utm codes from query string
53    const parentUrl = new URL(window.location.href)
54    const urlCodes = Object.fromEntries(
55      Array.from(parentUrl.searchParams.entries()).filter(([key]) =>
56        key.startsWith('utm_'),
57      ),
58    )
59
60    const utmCodes = {
61      ...urlCodes,
62    }
63
64    // Assign utm codes to iframe query string
65    const portalUrl = new URL(portal.src)
66
67    Object.entries(utmCodes).forEach(([key, code]) => {
68      portalUrl.searchParams.append(key, code)
69    })
70
71    portal.src = portalUrl.href
72    connected = true
73
74    document.removeEventListener(
75      'readystatechange',
76      addEventListenersToDocument,
77    )
78  }
79})('FRAME_ID')
80

Usage

Replace 'FRAME_ID' at the bottom of the script with the id of the iframe you want to embed.

Embed the iframe with the same ID and the following script

<script src="./iframe.js"></script>
<iframe
  id="FRAME_ID"
  src="https://example.com"
  style="border: 0px; width: 100%; margin: 1rem 0rem 2rem; min-height: 45rem;"
  allowfullscreen="true"
  sandbox="allow-same-origin allow-scripts allow-top-navigation-by-user-activation allow-popups allow-popups-to-escape-sandbox allow-forms"
  scrolling="no"
  width="100%"
  height="100%"
></iframe>