StylePropertyMapReadOnly
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
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
StylePropertyMapReadOnlyobject.
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...inloop (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
CSSStyleValueobjects containing the values for the provided property. StylePropertyMapReadOnly.has()-
Indicates whether the specified property is in the
StylePropertyMapReadOnlyobject. 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
StylePropertyMapReadOnlyobject.
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 inherited CSS property values. </p> <dl id="output"></dl> We add a touch of CSS with a custom property to better demonstrate the output:
p { --some-variable: 1.6em; --some-other-variable: translateX(33vw); --another-variable: 42; line-height: var(--some-variable); } 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 through 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 |