CSSFontFeatureValuesMap: has() method

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

The has() method of the CSSFontFeatureValuesMap interface returns a boolean indicating whether an entry with the specified key exists in this CSSFontFeatureValuesMap or not.

Syntax

js
has(property)

Parameters

key

The key of the value to return from the CSSFontFeatureValuesMap object.

Return value

The value associated with the specified key in the CSSFontFeatureValuesMap object. If the key can't be found, undefined is returned.

Examples

undefined

Basic usage

The following example returns true or false if the @swash rule contains the key. 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
// get the rules
const myRule = document.styleSheets[0].cssRules[0];
console.log(myRule.swash.has("swishy")); // logs true
console.log(myRule.swash.has("swooshy")); // logs false

Specifications

See also