CSSFontFeatureValuesMap: size property

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 size read-only property of the CSSFontFeatureValuesMap interface returns a positive integer containing the size of the CSSFontFeatureValuesMap object.

Value

A positive integer.

Examples

Basic usage

The following example outputs an integer of the number of the declarations within the @swash feature block. 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.size); // logs 2

Specifications

Specification

CSS Fonts Module Level 4
# cssfontfeaturevaluesmap

Browser compatibility

Enable JavaScript to view this browser compatibility table.

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This page was last modified on Feb 24, 2026 by MDN contributors.

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