swup swup Preload Plugin
GitHub swup on GitHub
Repo GitHub

Preload Plugin

A swup plugin for preloading pages and faster navigation.

  • Links with a data-swup-preload attribute will be preloaded automatically
  • Hovering a link on pointer devices will preload that link's URL, speeding up load time by a few 100ms. To save server resources, the number of simultaneous preload requests is limited to 5 by default.
  • Touch devices will instead preload links at the start of touch events, giving a ~80ms speed-up

Installation

Install the plugin from npm and import it into your bundle.

npm install @swup/preload-plugin

npm install @swup/preload-plugin

import SwupPreloadPlugin from '@swup/preload-plugin';

import SwupPreloadPlugin from '@swup/preload-plugin';

Or include the minified production file from a CDN:

<script src="https://unpkg.com/@swup/preload-plugin@3"></script>

<script src="https://unpkg.com/@swup/preload-plugin@3"></script>

Usage

To run this plugin, include an instance in the swup options.

const swup = new Swup({
  plugins: [new SwupPreloadPlugin()]
});

const swup = new Swup({
  plugins: [new SwupPreloadPlugin()]
});

Preloading

Hovering a link will automatically preload it.

<a href="/about">About</a> <!-- will preload when hovering -->

<a href="/about">About</a> <!-- will preload when hovering -->

To preload specific links, mark them with the data-swup-preload attribute.

<a href="/about" data-swup-preload>About</a>

<a href="/about" data-swup-preload>About</a>

To preload all links in a container, mark the container with data-swup-preload-all.

<nav data-swup-preload-all>
  <a href="/about">About</a>
  <a href="/contact">Contact</a>
</nav>

<nav data-swup-preload-all>
  <a href="/about">About</a>
  <a href="/contact">Contact</a>
</nav>

Options

throttle

Type: Number, Default: 5

The concurrency limit for simultaneous requests when hovering links on pointer devices.

preloadInitialPage

Type: Boolean, Default: True

The reasoning behind preloading the initial page is to allow instant back-button navigation after you've navigated away from it. In some instances this can cause issues, so you can disable it by setting this option to false.

Methods on the swup instance

The plugin adds two methods for preloading pages to the swup instance.

preload

Preload a single URL. Returns a promise that resolves when the pages was preloaded.

await swup.preload('/path/to/page');

await swup.preload('/path/to/page');

Scan the DOM for links with the attribute [data-swup-preload] and call preload for each URL:

swup.preloadLinks();

swup.preloadLinks();

Hooks

The plugin creates two new hooks.

page:preload

Fires when a page was preloaded.

swup.hooks.on('page:preload', (_visit, { page }) => console.log('preloaded:', page));

swup.hooks.on('page:preload', (_visit, { page }) => console.log('preloaded:', page));

Fires every time a link is hovered.

swup.hooks.on('link:hover', (_visit, { el }) => console.log('link hovered:', el));

swup.hooks.on('link:hover', (_visit, { el }) => console.log('link hovered:', el));