HighlightRegistry

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

The HighlightRegistry interface of the CSS Custom Highlight API is used to register Highlight objects to be styled using the API. It is accessed via CSS.highlights.

A HighlightRegistry instance is a Map-like object, in which each key is the name string for a custom highlight, and the corresponding value is the associated Highlight object.

Instance properties

The HighlightRegistry interface doesn't inherit any properties.

HighlightRegistry.size Read only

Returns the number of Highlight objects currently registered.

Instance methods

The HighlightRegistry interface doesn't inherit any methods.

HighlightRegistry.clear()

Remove all Highlight objects from the registry.

HighlightRegistry.delete()

Remove the named Highlight object from the registry.

HighlightRegistry.entries()

Returns a new iterator object that contains each Highlight object in the registry, in insertion order.

HighlightRegistry.forEach()

Calls the given callback once for each Highlight object in the registry, in insertion order.

HighlightRegistry.get()

Gets the named Highlight object from the registry.

HighlightRegistry.has()

Returns a boolean asserting whether a Highlight object is present the registry or not.

HighlightRegistry.keys()

An alias for HighlightRegistry.values().

HighlightRegistry.set()

Adds the given Highlight object to the registry with the given name, or updates the named Highlight object, if it already exists in the registry.

HighlightRegistry.values()

Returns a new iterator object that yields the Highlight objects in the registry, in insertion order.

Examples

Registering a highlight

The following example demonstrates how to create ranges, instantiate a new Highlight object for them, and register the highlight using the HighlightRegistry, to style it on the page:

HTML

html
<p id="foo">CSS Custom Highlight API</p>

CSS

css
::highlight(my-custom-highlight) {
  background-color: peachpuff;
}

JavaScript

js
const text = document.getElementById("foo").firstChild;

if (!CSS.highlights) {
  text.textContent =
    "The CSS Custom Highlight API is not supported in this browser!";
}

// Create a couple of ranges.
const range1 = new Range();
range1.setStart(text, 0);
range1.setEnd(text, 3);

const range2 = new Range();
range2.setStart(text, 21);
range2.setEnd(text, 24);

// Create a custom highlight for these ranges.
const highlight = new Highlight(range1, range2);

// Register the ranges in the HighlightRegistry.
CSS.highlights.set("my-custom-highlight", highlight);

Result

Specifications

Specification
CSS Custom Highlight API Module Level 1
# highlight-registry

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
HighlightRegistry
[Symbol.iterator]
clear
delete
entries
forEach
get
has
keys
set
size
values

Legend

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Full support
Full support
In development. Supported in a pre-release version.
In development. Supported in a pre-release version.
No support
No support
See implementation notes.

See also