Web/API/StylePropertyMapReadOnly

This is an experimental technologyCheck the Browser compatibility table carefully before using this in production.

The StylePropertyMapReadOnly interface of the the CSS Typed Object Model API provides a read-only representation of a CSS declaration block that is an alternative to CSSStyleDeclaration. Retrieve an instance of this interface using Element.computedStyleMap().

Properties

StylePropertyMapReadOnly.size

Returns an unsinged long integer containing the size of the StylePropertyMapReadOnly object.

Methods

StylePropertyMapReadOnly.entries()

Returns an array of a given object's own enumerable property [key, value] pairs, in the same order as that provided by a for...in loop (the difference being that a for-in loop enumerates properties in the prototype chain as well).

StylePropertyMapReadOnly.forEach()

Executes a provided function once for each element of StylePropertyMapReadOnly.

StylePropertyMapReadOnly.get()

Returns the value of the specified property.

StylePropertyMapReadOnly.getAll()

Returns an array of CSSStyleValue objects containing the values for the provided property.

StylePropertyMapReadOnly.has()

Indicates whether the specified property is in the StylePropertyMapReadOnly object.

StylePropertyMapReadOnly.keys()

Returns a new Array Iterator containing the keys for each item in StylePropertyMapReadOnly.

StylePropertyMapReadOnly.values()

Returns a new Array Iterator containing the values for each index in the StylePropertyMapReadOnly object.

Examples

We have to have an element to observe:

<p>
   This is a paragraph with some text. We can add some CSS, or not. The 
   style map will include all the default and inherted CSS property values.
</p>
<dl id="output"></dl>

We add a touch of CSS with a custom property to better demonstrate the output:

p { 
   --someVariable: 1.6em;
   --someOtherVariable: translateX(33vw);
   --anotherVariable: 42;
   line-height: var(--someVariable);
}

We add JavaScript to grab our paragraph and return back a definition list of all the default CSS property values using computedStyleMap().

// get the element
const myElement = document.querySelector('p');

// get the <dl> we'll be populating
const stylesList = document.querySelector('#output');

// Retrieve all computed styles with computedStyleMap()
const stylePropertyMap = myElement.computedStyleMap();

// iterate thru the map of all the properties and values, adding a <dt> and <dd> for each
for (const [prop, val] of stylePropertyMap) {
    // properties
    const cssProperty = document.createElement('dt');
    cssProperty.appendChild(document.createTextNode(prop));
    stylesList.appendChild(cssProperty);

    // values
    const cssValue = document.createElement('dd');
    cssValue.appendChild(document.createTextNode(val));
    stylesList.appendChild(cssValue);
}

Specifications

Specification	Status	Comment
CSS Typed OM Level 1The definition of 'StylePropertyMapReadOnly' in that specification.	Working Draft	Initial definition.

Browser compatibility

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
StylePropertyMapReadOnly Experimental'	Chrome Full support 66	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 53	Safari No support No	WebView Android Full support 66	Chrome Android Full support 66	Firefox Android No support No	Opera Android Full support 47	Safari iOS No support No	Samsung Internet Android Full support 9.0
entries Experimental'	Chrome Full support 66	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 53	Safari No support No	WebView Android Full support 66	Chrome Android Full support 66	Firefox Android No support No	Opera Android Full support 47	Safari iOS No support No	Samsung Internet Android Full support 9.0
forEach Experimental'	Chrome Full support 66	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 53	Safari No support No	WebView Android Full support 66	Chrome Android Full support 66	Firefox Android No support No	Opera Android Full support 47	Safari iOS No support No	Samsung Internet Android Full support 9.0
get Experimental'	Chrome Full support 66	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 53	Safari No support No	WebView Android Full support 66	Chrome Android Full support 66	Firefox Android No support No	Opera Android Full support 47	Safari iOS No support No	Samsung Internet Android Full support 9.0
getAll Experimental'	Chrome Full support 66	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 53	Safari No support No	WebView Android Full support 66	Chrome Android Full support 66	Firefox Android No support No	Opera Android Full support 47	Safari iOS No support No	Samsung Internet Android Full support 9.0
has Experimental'	Chrome Full support 66	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 53	Safari No support No	WebView Android Full support 66	Chrome Android Full support 66	Firefox Android No support No	Opera Android Full support 47	Safari iOS No support No	Samsung Internet Android Full support 9.0
keys Experimental'	Chrome Full support 66	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 53	Safari No support No	WebView Android Full support 66	Chrome Android Full support 66	Firefox Android No support No	Opera Android Full support 47	Safari iOS No support No	Samsung Internet Android Full support 9.0
size Experimental'	Chrome Full support 66	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 53	Safari No support No	WebView Android Full support 66	Chrome Android Full support 66	Firefox Android No support No	Opera Android Full support 47	Safari iOS No support No	Samsung Internet Android Full support 9.0
values Experimental'	Chrome Full support 66	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 53	Safari No support No	WebView Android Full support 66	Chrome Android Full support 66	Firefox Android No support No	Opera Android Full support 47	Safari iOS No support No	Samsung Internet Android Full support 9.0
@@iterator Experimental'	Chrome Full support 66	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 53	Safari No support No	WebView Android Full support 66	Chrome Android Full support 66	Firefox Android No support No	Opera Android Full support 47	Safari iOS No support No	Samsung Internet Android Full support 9.0

Legend

Full support  

Full support

No support  

No support

Experimental. Expect behavior to change in the future.'

Experimental. Expect behavior to change in the future.

StylePropertyMapReadOnly by Mozilla Contributors is licensed under CC-BY-SA 2.5.