CSSMathSum

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.

CSSStyleValue CSSNumericValue CSSMathValue CSSMathSum

Constructor

CSSMathSum() Experimental

Creates a new CSSMathSum object.

Instance properties

CSSMathSum.values Experimental

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

Static methods

The interface may also inherit methods from its parent interface, CSSMathValue.

Instance methods

The interface may also inherit methods from its parent interface, CSSMathValue.

Event handlers

No

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 1
# cssmathsum

Browser compatibility

BCD tables only load in the browser