StylePropertyMapReadOnly
Experimental
This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The StylePropertyMapReadOnly
interface of 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 afor...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 Element.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.innerText = prop;
stylesList.appendChild(cssProperty);
// values
const cssValue = document.createElement('dd');
cssValue.innerText = val;
stylesList.appendChild(cssValue);
}
Specifications
Specification | Status | Comment |
---|---|---|
CSS Typed OM Level 1 The definition of 'StylePropertyMapReadOnly' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
BCD tables only load in the browser