lazyvids.js

A small utility to lazy-load autoplay HTML5 videos once they enter the viewport.

Installation

Install using your favourite package manager.

$ yarn add lazyvids

Import into your project.

import 'lazyvids';

Usage

lazyvids.js works by setting attributes on HTML5 video elements, and playing the videos once they are scrolled into view.

1. Add a [data-lazyvids] attribute to <video> elements that you want to lazy-play.

2. Add preload="none" to the <video> to prevent the browser from downloading it when out of view. preload="metadata" is preferred, but does not work as it should in Safari (🙄).

3. It's best practice to also include muted and playsinline attributes, but the library will add them by default.

4. Provide the <video> with a poster image attribute.

<video
  data-lazyvids
  muted
  playsinline
  preload="none"
  poster="poster.jpg"
  src="example.mp4"
></video>

<video data-lazyvids muted playsinline preload="none" poster="poster.jpg">
  <source src="example.webm" type="video/webm" />
  <source src="example.mp4" type="video/mp4" />
</video>

Options

Configuration options are available using a lazyvidsConfig object on the global window object.

<script>
  window.lazyvidsConfig = lazyvidsConfig || {};
  lazyvidsConfig = {
    logLevel: 'silent',
    ignoreHidden: false,
    minBandwidth: 0,
    reduceData: false,
  };
</script>

Option	Type	Default Value	Description
logLevel	string	silent	Set logging level: verbose, warn, silent.
ignoreHidden	boolean	false	Set whether to skip <video> elements with display: hidden.
minBandwidth	number	0	If reduceData is true, set threshold above which videos will play.
reduceData	boolean	false	If true, will not play videos if data saver is enabled or bandwidth is below minBandwidth.