wicg-inert
v3.1.3
Published
A polyfill for the proposed inert API
Downloads
477,932
Readme
The inert
attribute/property allows web authors to mark parts of the DOM tree
as inert:
When a node is inert, then the user agent must act as if the node was absent for the purposes of targeting user interaction events, may ignore the node for the purposes of text search user interfaces (commonly known as "find in page"), and may prevent the user from selecting text in that node.
Furthermore, a node which is inert should also be hidden from assistive technology.
Details
- Read the Explainer.
- Read the Spec.
- Try the Demo.
- Give feedback!
Polyfill
Installation
npm install --save wicg-inert
We recommend only using versions of the polyfill that have been published to npm, rather than cloning the repo and using the source directly. This helps ensure the version you're using is stable and thoroughly tested.
This project provides two versions of the polyfill in package.json
.
main
: Points atdist/inert.js
which is transpiled to ES3.module
: Points atdist/inert.esm.js
which is transpiled to ES3.
If you do want to build from source, make sure you clone the latest tag!
Usage
1. Either import the polyfill, or add the script to your page
import "wicg-inert";
OR…
...
<script src="/node_modules/wicg-inert/dist/inert.min.js"></script>
</body>
</html>
2. Toggle inert
on an element
const el = document.querySelector('#my-element');
el.inert = true; // alternatively, el.setAttribute('inert', '');
Legacy Browser Support
If you want to use inert
with an older browser you'll need to include
additional polyfills for
Map,
Set,
Element.prototype.matches,
and Node.prototype.contains.
In accordance with the W3C's new polyfill
guidance,
the inert
polyfill does not bundle other polyfills.
You can use a service like https://cdnjs.cloudflare.com/polyfill to download only the polyfills needed by the current browser. Just add the following line to the start of your page:
<script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.min.js?version=4.8.0&features=Map%2CSet%2CElement.prototype.matches%2CNode.prototype.contains"></script>
Strict Content Security Policy
By default, this polyfill will dynamically insert some CSS, which requires the style-src rule of your Content Security Policy to allow 'unsafe-inline'.
It is possible avoid doing so by including those rules from a CSS stylesheet, as
follows (the id
property is used by the polyfill to know if it needs to
dynamically add the missing rules):
<link rel="stylesheet" type="text/css" href="inert.css" id="inert-style" />
The stylesheet should include the following rules:
[inert] {
pointer-events: none;
cursor: default;
}
[inert], [inert] * {
user-select: none;
-webkit-user-select: none;
-ms-user-select: none;
}
Performance and gotchas
The polyfill attempts to provide a reasonable fidelity polyfill for the inert
attribute, however please note:
It relies on mutation observers to detect the addition of the
inert
attribute, and to detect dynamically added content within inert subtrees. Testing for inert-ness in any way immediately after either type of mutation will therefore give inconsistent results; please allow the current task to end before relying on mutation-related changes to take effect, for example viasetTimeout(fn, 0)
orPromise.resolve()
.Example:
const newButton = document.createElement('button');
const inertContainer = document.querySelector('[inert]');
inertContainer.appendChild(newButton);
// Wait for the next microtask to allow mutation observers to react to the
// DOM change
Promise.resolve().then(() => {
expect(isUnfocusable(newButton)).to.equal(true);
});
Using the
inert
property, however, is synchronous.The polyfill will be expensive, performance-wise, compared to a native
inert
implementation, because it requires a fair amount of tree-walking. To mitigate this, we recommend not usinginert
during performance sensitive actions (like during animations or scrolling). Instead, wait till these events are complete, or consider using requestIdleCallback to setinert
.
Testing
Tests are written using ES5 syntax. This is to avoid needing to transpile them
for older browsers. There are a few modern features they rely upon, e.g.
Array.from
and Promises
. These are polyfilled for the tests using
https://cdnjs.cloudflare.com/polyfill. For a list of polyfilled features, check out
the polyfill
section in karma.conf.js
.
Big Thanks
Cross-browser Testing Platform and Open Source <3 Provided by Sauce Labs