CSSFontFeatureValuesMap: forEach() method

Limited availability

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

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The forEach() method of CSSFontFeatureValuesMap instances executes a provided function once per each key/value pair in this map, in insertion order.

Syntax

js
forEach(callbackFn)
forEach(callbackFn, thisArg)

Parameters

callbackFn

A function to execute for each entry in the map. The function is called with the following arguments:

value

Value of each iteration.

key

Key of each iteration.

map

The map being iterated.

thisArg Optional

A value to use as this when executing callbackFn.

Return value

None (undefined).

Examples

Basic usage

The following example logs the key and value for each entry in the @swash rule. This example is using @swash but also works with other feature value blocks.

CSS

css
@font-feature-values "MonteCarlo" {
  @swash {
    swishy: 1;
    swashy: 2;
  }
}

JavaScript

js
// function to be used as callback
function logSwashes(value, key, map) {
  console.log(`('${key}') = ${value}`);
}
// get the rules
const myRule = document.styleSheets[0].cssRules[0];
myRule.swash.forEach(logSwashes);
// logs:
// "('swishy') = 1"
// "('swashy') = 2"