lazyvids

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. A poster image is required for the video to lazy-play by default, but this behaviour can be changed using the relevant lazyvidsConfig option.

<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. This must be included in the HTML before the lazyvids script.

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

Option	Type	Default Value	Description
logLevel	string	silent	Set logging level: verbose, warn, silent.
ignoreHidden	boolean	false	Set whether to skip <videos> with display: hidden.
minBandwidth	number	0	If reducedData 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.
requirePoster	boolean	true	When false, will lazy-play video even if poster image is missing.