HighlightRegistry: forEach() method

Baseline 2025

Newly available

Since June 2025, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

The forEach() method of the HighlightRegistry interface executes a provided function once for each Highlight object in the registry, in insertion order.

HighlightRegistry is a Map-like object, so this is similar to using Map.forEach().

Syntax

forEach(callbackFn)
forEach(callbackFn, thisArg)

Parameters

callback

Function to execute for each Highlight object, taking three arguments:

highlight: The current highlight.
name: The highlight name.
registry: The registry object which forEach() was called upon.

thisArg

Value to use as this when executing callbackFn.

Return value

None (undefined).

Examples

The code snippet below shows how create a new highlight with two ranges, and then log the ranges by using the forEach() method:

function logAllHighlights(highlight, name) {
  console.log(`Highlight ${name} exists in the registry`, highlight);
}

const customHighlight1 = new Highlight();
const customHighlight2 = new Highlight();
const customHighlight3 = new Highlight();

CSS.highlights.set("custom-highlight-1", customHighlight1);
CSS.highlights.set("custom-highlight-2", customHighlight2);
CSS.highlights.set("custom-highlight-3", customHighlight3);

CSS.highlights.forEach(logAllHighlights);

Specifications

Specification
ECMAScript® 2026 Language Specification # sec-map.prototype.foreach