Faster subsequent page-loads by prefetching in-viewport links during idle time
Faster subsequent page-loads by prefetching in-viewport links during idle time
Quicklink attempts to make navigations to subsequent pages load faster. It:
navigator.connection.effectiveType) or has data-saver enabled (using navigator.connection.saveData)<link rel=prefetch> or XHR). Provides some control over the request priority (can switch to fetch() if supported).This project aims to be a drop-in solution for sites to prefetch links based on what is in the user's viewport. It also aims to be small (< 1KB minified/gzipped).
npm install --save quicklink
You can also grab quicklink from unpkg.com/quicklink.
Once initialized, quicklink will automatically prefetch URLs for links that are in-viewport during idle time.
Quickstart:
<!-- Include quicklink from dist -->
<script src="dist/quicklink.umd.js"></script>
<!-- Initialize (you can do this whenever you want) -->
<script>
quicklink();
</script>
For example, you can initialize after the load event fires:
<script>
window.addEventListener('load', () =>{
quicklink();
});
</script>
ES Module import:
import quicklink from "quicklink/dist/quicklink.mjs";
quicklink();
The above options are best for multi-page sites. Single-page apps have a few options available for using quicklink with a router:
quicklink() once a navigation to a new route has completedquicklink() against a specific DOM element / componentquicklink({urls:[...]}) with a custom set of URLs to prefetchquicklink accepts an optional options object with the following parameters:
el: DOM element to observe for in-viewport links to prefetchurls: Static array of URLs to prefetch (instead of observing document or a DOM element links in the viewport)timeout: Integer for the requestIdleCallback timeout. A time in milliseconds by which the browser must execute prefetching. Defaults to 2 seconds.timeoutFn: Function for specifying a timeout. Defaults to requestIdleCallback. Can also be swapped out for a custom function like networkIdleCallback (see demos)priority: Boolean specifying preferred priority for fetches. Defaults to false. true will attempt to use the fetch() API where supported (rather than rel=prefetch)origins: Static array of URL hostname strings that are allowed to be prefetched. Defaults to the same domain origin, which prevents any cross-origin requests.ignores: A RegExp, Function, or Array that further determines if a URL should be prefetched. These execute after origin matching.TODO:
quicklink:
IntersectionObserver to be supported (see CanIUse). We recommend conditionally polyfilling this feature with a service like Polyfill.io:<script src="https://polyfill.io/v3/polyfill.min.js?features=IntersectionObserver"></script>
Alternatively, see the Intersection Observer polyfill.
Defaults to 2 seconds (via requestIdleCallback). Here we override it to 4 seconds:
quicklink({
timeout: 4000
});
Defaults to document otherwise.
const elem = document.getElementById('carousel');
quicklink({
el: elem
});
If you would prefer to provide a static list of URLs to be prefetched, instead of detecting those in-viewport, customizing URLs is supported.
quicklink({
urls: ['2.html','3.html', '4.js']
});
Defaults to low-priority (rel=prefetch or XHR). For high-priority (priority: true), attempts to use fetch() or falls back to XHR.
quicklink({ priority: true });
Provide a list of hostnames that should be prefetch-able. Only the same origin is allowed by default.
Important: You must also include your own hostname!
quicklink({
origins: [
// add mine
'my-website.com',
'api.my-website.com',
// add third-parties
'other-website.com',
'example.com',
// ...
]
});
Enables all cross-origin requests to be made.
quicklink({
origins: true,
// or
origins: []
});
These filters run after the origins matching has run. Ignores can be useful for avoiding large file downloads or for responding to DOM attributes dynamically.
// Same-origin restraint is enabled by default.
//
// This example will ignore all requests to:
// - all "/api/*" pathnames
// - all ".zip" extensions
// - all <a> tags with "noprefetch" attribute
//
quicklink({
ignores: [
/\/api\/?/,
uri => uri.includes('.zip'),
(uri, elem) => elem.hasAttribute('noprefetch')
]
});
You may also wish to ignore prefetches to URLs which contain a URL fragment (e.g. index.html#top). This can be useful if you (1) are using anchors to headings in a page or (2) have URL fragments setup for a single-page application, and which to avoid firing prefetches for similar URLs.
Using ignores this can be achieved as follows:
quicklink({
ignores: [
uri => uri.includes('#')
// or RegExp: /#(.+)/
// or element matching: (uri, elem) => !!elem.hash
]
});
The prefetching provided by quicklink can be viewed as a progressive enhancement. Cross-browser support is as follows:
Set() and Array.from() shims. Projects like es6-shim are an alternative you can consider.Certain features have layered support:
navigator.connection.effectiveType) is only available in Chrome 61+ and Opera 57+{priority: true} and the Fetch API isn't available, XHR will be used instead.quicklink includes a prefetcher that can be individually imported for use in other projects. After installing quicklink as a dependency, you can use it as follows:
<script type="module">
import prefetch from '../src/prefetch.mjs';
const urls = ['1.html', '2.html'];
const promises = urls.map(url => prefetch(url));
Promise.all(promises);
</script>
Here's a WebPageTest run for our demo improving page-load performance by up to 4 seconds via quicklink's prefetching. A video comparison of the before/after prefetching is on YouTube.
For demo purposes, we deployed a version of the Google Blog on Firebase hosting. We then deployed another version of it, adding quicklink to the homepage and benchmarked navigating from the homepage to an article that was automatically prefetched. The prefetched version loaded faster.
Please note: this is by no means an exhaustive benchmark of the pros and cons of in-viewport link prefetching. Just a demo of the potential improvements the approach can offer. Your own mileage may heavily vary.
Cross-origin prefetching (e.g a.com/foo.html prefetches b.com/bar.html) has a number of limitations. One such limitation is with session-stitching. b.com may expect a.com's navigation requests to include session information (e.g a temporary ID - e.g b.com/bar.html?hash=<>×tamp=<>), where this information is used to customize the experience or log information to analytics. If session-stitching requires a timestamp in the URL, what is prefetched and stored in the HTTP cache may not be the same as the one the user ultimately navigates to. This introduces a challenge as it can result in double prefetches.
To workaround this problem, you can consider passing along session information via the ping attribute (separately) so the origin can stitch a session together asynchronously.
Intersection Observer to prefetch all of the links that are in view and provided heavy inspiration for this project.Licensed under the Apache-2.0 license.
1.0.1 (2019-08-17)
requestIdleCallback exists in window (#112) (089da91), closes #112<script> tags (e735eb7)FAQs
Faster subsequent page-loads by prefetching in-viewport links during idle time
The npm package quicklink receives a total of 10,213 weekly downloads. As such, quicklink popularity was classified as popular.
We found that quicklink demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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