CSSPropertyRule: initialValue property

Baseline 2024

Newly available

Since July 2024, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

The read-only initialValue nullable property of the CSSPropertyRule interface returns the initial value of the custom property registration represented by the @property rule, controlling the property's initial value.

Value

A string which is a <declaration-value>.

Examples

This stylesheet contains a single @property rule. The first CSSRule returned will be a CSSPropertyRule representing this rule. The initialValue property returns the string "#c0ffee" this being the value of the initial-value property in the CSS.

css
@property --property-name {
  syntax: "<color>";
  inherits: false;
  initial-value: #c0ffee;
}

js
const myRules = document.styleSheets[0].cssRules;
console.log(myRules[0].initialValue); // "#c0ffee"

Specifications

Specification

CSS Properties and Values API Level 1
# dom-csspropertyrule-initialvalue

Browser compatibility

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This page was last modified on Jun 10, 2025 by MDN contributors.

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CSS Properties and Values API
CSSPropertyRule
Instance properties
Inheritance
1. CSSRule
Related pages for CSS Properties and Values API
1. CSS.registerProperty
Guides
1. Using the CSS properties and values API