@newswire/frames

@newswire/frames is a minimalistic take on responsive iframes in the spirit of Pym.js.

Key features

• 🐜 <1 kilobyte gzipped for both parent and frame code
• 🌴 Tree-shakable - import only what you need for your use case
• ⚡️ Speaks AMP and is compatible with amp-iframe
• 🕰 Legacy Pym.js support - recognizes height updates from Pym.js iframes
• 🧪 Fully tested in Safari, Chrome and Firefox with Playwright

Supported browsers

Installation

@newswire/frames is available via npm.

npm install @newswire/frames

You can also use it directly via unpkg.com.

<script src="https://unpkg.com/@newswire/frames/dist/index.umd.js"></script>
<!-- Now available at `window.newswireFrames` -->

You can also import it as a module via unpkg!

<script type="module">
	import * as frames from 'https://unpkg.com/@newswire/frames/dist/index.mjs';

	frames.autoInitFrames();
</script>

Usage

From the host page (framer or parent)

The page that contains the embeds needs to use the Framer class to set up instances for each embed.

Assume we have the following markup in our HTML:

<div id="embed-container">Loading...</div>

Then, in our script:

import { Framer } from '@newswire/frames';

const container = document.getElementById('embed-container');
const src = 'https://i-am-an-embed/';
const attributes = { sandbox: 'allow-scripts allow-same-origin' };

const framer = new Framer(container, { src, attributes });
// Now the iframe has been added to the page and is listening for height changes notifications from within the iframe

It is also possible to observe existing iframes on a page if the content of the frames are compatible with @newswire/frames. This is handy if you already have your own method to dynamically add iframes to the page, or are using a custom method to lazy load them and don't need the heavy hand of Framer.

import { observeIframe } from '@newswire/frames';

// grab a reference to an existing iframe
const iframe = document.getElementById('my-embed');

// returns a `unobserve()` function if you need to stop listening
const unobserve = observeIframe(iframe);

// later, if you need to disconnect from the iframe
unobserve();

Pym.js had the ability to automatically initialize embeds that had matching attibutes on their container elements — @newswire/frames can do this as well.

Assume we have the following markup in our HTML:

<div data-frame-src="https://i-am-an-embed/"></div>
<div data-frame-src="https://i-am-an-embed-too/"></div>
<div data-frame-src="https://i-am-an-embed-three/"></div>

Then in our script, we can skip the fanfare of setting up a Framer for each one and use the data-frame-src attribute to find them.

import { autoInitFrames } from '@newswire/frames';

// looks for any elements with `data-frame-src` that haven't been initialized yet, and sets them up
autoInitFrames();

If you're needing to pass any of the other options to Framer when you're automatically creating the embeds, you can add attributes that the initializer will pick up and pass along using the data-frame-attribute-* prefix.

<div
	data-frame-src="https://i-am-an-embed/"
	data-frame-attribute-sandbox="allow-scripts allow-same-origin"
></div>

<!-- This creates... -->
<iframe src="https://i-am-an-embed/" sandbox="allow-scripts allow-same-origin">
</iframe>

From the embedded page (frame or child)

While the code to setup the host page is similar to Pym's Parent class, the methods for making the iframed page communicate with the host page are a little different.

Want to set it and forget it? You can import a function that sets up listeners and sends the initial height of the frame's content.

import { initFrame } from '@newswire/frames';

// 1. Sends the initial frame's content height
// 2. Sets up an one-time istener to send the height on load
// 3. Sets up a listener to send the height every time the frame resizes
// 4. Sets up an event listener that sends the height once the parent window begins watching
initFrame();

You can also automatically set up long polling for height changes as well.

import { initFrameAndPoll } from '@newswire/frames';

// 1. Sends the initial frame's content height
// 2. Sets up an one-time listener to send the height on load
// 3. Sets up a listener to send the height every time the frame resizes
// 4. Sets up an event listener that sends the height once the parent window begins watching
// 5. Sets up an interval to send a new height update every 300ms
initFrameAndPoll();

Alternatively, you can set and use function independently depending on the needs of your frame's content.

import {
	sendFrameHeight,
	sendHeightOnLoad,
	sendHeightOnResize,
	sendHeightOnPoll,
	sendHeightOnFramerInit,
} from '@newswire/frames';

// 1. Sends the initial frame's content height
sendFrameHeight();

// 2. Sets up an one-time listener to send the height on load
sendHeightOnLoad();

// 3. Sets up a listener to send the height every time the frame resizes
sendHeightOnResize();

// 4. Sets up an event listener that sends the height once the parent window begins watching
sendHeightOnFramerInit();

// 5. Sets up an interval to send a new height update every 150ms
sendHeightOnPoll(150);

// 1-4 is identical to initFrame()! 1-5 is identical to initFrameAndPoll()!

Typically using initFrame() will be enough, but if you have code that will potentially change the height of the frame's content (like with an <input> or <button> press) and would rather not use polling, you can use sendFrameHeight() to manually recalculate and send an update to the parent page.

Legacy Pym.js support

@newswire/frames (1.0.0+) can be a drop-in replacement for Pym.js on host/parent pages, but it only understands height events sent from Pym.js-powered child frames. All other events will be ignored. Unless you were doing something exotic or extremely bespoke with Pym.js odds are it will work!

API

Table of Contents

• observeIframe
  • Parameters
  • Examples
• FramerOptions
  • Properties
• Framer
  • Parameters
• autoInitFrames
  • Examples
• sendFrameHeight
  • Parameters
  • Examples
• sendHeightOnLoad
  • Examples
• sendHeightOnResize
  • Examples
• sendHeightOnFramerInit
  • Examples
• sendHeightOnPoll
  • Parameters
  • Examples
• initFrame
  • Examples
• initFrameAndPoll
  • Parameters
  • Examples

observeIframe

Adds an event listener to an existing iframe for receiving height change messages. Also tells the iframe that we're listening and requests the initial height. Returns an unobserve() function for later removing the listener.

Parameters

• iframe HTMLIFrameElement the iframe to observe

Examples

// grab a reference to an existing iframe
const iframe = document.getElementById('my-embed');

// returns a `unobserve()` function if you need to stop listening
const unobserve = observeIframe(iframe);

// later, if you need to disconnect from the iframe
unobserve();

FramerOptions

Type: object

Properties

• src (string | null)? the URL to set as the src of the iframe
• attributes Record<string, string>? any attributes to add to the iframe itself

Framer

The Framer function to be called in the host page. A wrapper around interactions with a created iframe. Returns a remove() function for disconnecting the event listener and removing the iframe from the DOM.

Parameters

• container Element the containing DOM element for the iframe

• options FramerOptions (optional, default {})

  • options.attributes
  • options.src

autoInitFrames

Automatically initializes any frames that have not already been auto-activated.

Examples

// sets up all frames that have not been initialized yet
autoInitFrames();

sendFrameHeight

Sends the current document's height or provided value to the host window using postMessage.

Parameters

• height number? The height to pass to the host page, is determined automatically if not passed (optional, default getDocumentHeight())

Examples

// Uses the document's height to tell the host page
sendFrameHeight();

// Pass a height you've determined in another way
sendFrameHeight(500);

Returns void

sendHeightOnLoad

Sets up an event listener for the load event that sends the new frame height to the host. Automatically removes itself once fired.

Examples

// once the frame's load event is fired, tell the host page its new height
sendHeightOnLoad();

Returns void

sendHeightOnResize

Sets up an event listener for the resize event that sends the new frame height to the host.

Examples

// every time the frame is resized, tell the host page what its new height is
sendHeightOnResize();

Returns void

sendHeightOnFramerInit

Sets up an event listener for a message from the parent window that it is now listening for messages from this iframe, and tells it the iframe's height at that time. This makes it possible to delay observing an iframe (e.g. when lazy loading) but trust the parent will get the current height ASAP.

Examples

// as soon as a Framer connects, tell the host page what the current height is
sendHeightOnFramerInit();

Returns void

sendHeightOnPoll

Sends height updates to the host page on an interval.

Parameters

• delay number? How long to set the interval (optional, default 300)

Examples

// will call sendFrameHeight every 300ms
sendHeightOnPoll();

// will call sendFrameHeight every 150ms
sendHeightOnPoll(150);

Returns void

initFrame

A helper for running the standard functions for setting up a frame.

Automatically calls an sendFrameHeight, sendHeightOnLoad, sendHeightOnResize and sendHeightOnFramerInit.

Examples

initFrame();

Returns void

initFrameAndPoll

Calls initFrame to setup a frame, then initializes a poller to continue to update on an interval.

Parameters

• delay number? An optional custom delay to pass to sendHeightOnPoll

Examples

// calls initFrame, then calls sendHeightOnPoll
initFrameAndPoll();

Returns void

License

MIT