Draft
This page is not complete.

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

The CSSMathSum interface of the CSS Typed Object Model API 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 whosevalue 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'

Specifications

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

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
CSSMathSum
Experimental
Chrome Full support 66Edge No support NoFirefox No support NoIE No support NoOpera Full support 53Safari No support NoWebView Android Full support 66Chrome Android Full support 66Firefox Android No support NoOpera Android Full support 47Safari iOS No support NoSamsung Internet Android Full support Yes
CSSMathSum() constructor
Experimental
Chrome Full support 66Edge No support NoFirefox No support NoIE No support NoOpera Full support 53Safari No support NoWebView Android Full support 66Chrome Android Full support 66Firefox Android No support NoOpera Android Full support 47Safari iOS No support NoSamsung Internet Android ?
values
Experimental
Chrome Full support 66Edge No support NoFirefox No support NoIE No support NoOpera Full support 53Safari No support NoWebView Android Full support 66Chrome Android Full support 66Firefox Android No support NoOpera Android Full support 47Safari iOS No support NoSamsung Internet Android Full support Yes

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.

Document Tags and Contributors

Contributors to this page: estelle, chrisdavidmills, liruiqi, jpmedley
Last updated by: estelle,