StylePropertyMapReadOnly
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()
.
Instance properties
StylePropertyMapReadOnly.size
-
Returns an unsigned long integer containing the size of the
StylePropertyMapReadOnly
object.
Instance 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:
html
<p>
This is a paragraph with some text. We can add some CSS, or not. The style map
will include all the default and inherited CSS property values.
</p>
<dl id="output"></dl>
We add a touch of CSS with a custom property to better demonstrate the output:
css
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()
.
js
// 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 |
---|
CSS Typed OM Level 1 # the-stylepropertymap |
Browser compatibility
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