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HighlightRegistry

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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.

  • size Read only
    • : Returns the number of Highlight objects currently registered.

Instance methods

The HighlightRegistry interface doesn’t inherit any methods.

  • clear()
    • : Remove all Highlight objects from the registry.
  • delete()
    • : Remove the named Highlight object from the registry.
  • entries()
    • : Returns a new iterator object that contains each Highlight object in the registry, in insertion order.
  • forEach()
    • : Calls the given callback once for each Highlight object in the registry, in insertion order.
  • get()
    • : Gets the named Highlight object from the registry.
  • has()
    • : Returns a boolean asserting whether a Highlight object is present the registry or not.
  • highlightsFromPoint()
    • : Returns an array of objects representing the custom highlights applied at a specific point within the viewport.
  • keys()
  • 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.
  • 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

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

CSS

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

JavaScript

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

Interactive exampleOpen the canonical MDN source to run this embedded demo.

Specifications

SpecificationsStandards references are available on the canonical MDN page.

Browser compatibility

Browser compatibilityCompatibility data is available on the canonical MDN page.

See also