CSSMathSum

Draft: This page is not complete.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The CSSMathSum interface of the CSS_Object_Model#css_typed_object_model represents the result obtained by calling add(), sub(), or toSum() on CSSNumericValue.

A CSSMathSum is the object type returned when the StylePropertyMapReadOnly.get() method is used on a CSS property whose value is created with a calc() function.

Constructor

CSSMathSum.CSSMathSum()

Creates a new CSSMathSum object.

Properties

CSSMathSum.values

Returns a CSSNumericArray object which contains one or more CSSNumericValue objects.

Event handlers

No

Methods

None.

Examples

We create an element with a width determined using a calc() function, then console.log() the operator and values, and dig into the values a bit.

<div>has width</div>

We assign a width

div {
  width: calc(30% - 20px);
}

We add the JavaScript

const styleMap = document.querySelector('div').computedStyleMap();

console.log( styleMap.get('width') );                  // CSSMathSum {values: CSSNumericArray, operator: "sum"}
console.log( styleMap.get('width').operator );         // 'sum'
console.log( styleMap.get('width').values );           // CSSNumericArray {0: CSSUnitValue, 1: CSSUnitValue, length: 2}
console.log( styleMap.get('width').values[0] );        // CSSUnitValue {value: 30, unit: "percent"}
console.log( styleMap.get('width').values[0].value );  // 30
console.log( styleMap.get('width').values[0].unit );   // 'percent'
console.log( styleMap.get('width').values[1] );        // CSSUnitValue {value: -20, unit: "px"}
console.log( styleMap.get('width').values[1].value );  //  -20
console.log( styleMap.get('width').values[1].unit );   // 'px'

The specification is still evolving. In the future we may write the last three lines as:

console.log( styleMap.get('width').values[1] );            // CSSMathNegate {value: CSSUnitValue, operator: "negate"}
console.log( styleMap.get('width').values[1].value );      // CSSUnitValue {value: 20, unit: "px"}
console.log( styleMap.get('width').values[1].value.unit ); // 'px'

Specifications

Specification
CSS Typed OM Level 2 (CSS Typed OM 2)
# cssmathsum

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
CSSMathSum
66
79
No
No
53
No
66
66
No
47
No
9.0
CSSMathSum
66
79
No
No
53
No
66
66
No
47
No
9.0
values
66
79
No
No
53
No
66
66
No
47
No
9.0

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https://developer.mozilla.org/en-US/docs/Web/API/CSSMathSum