Units

Parse length and angle CSS values and convert between units.

#### Supported units:

Length: %, ch, cm, em, ex, in, mm, pc, pt, px, rem, vh, vmax, vmin, vw

Angle: deg, grad, rad, turn

Install

Bower: bower install -S units-css

npm: npm i -S units-css

(One object is exported:)

``javascript
var units = require('units-css');
`

API

$3

Extract the numeric value and unit from a formatted CSS value:

`javascript
units.parse('1px'); // {'value': 1, 'unit': 'px'}
`

Or, passing only a value or only a unit:

`javascript
units.parse(1); // {'value': 1, 'unit': ''}
units.parse('px'); // {'value': 0, 'unit': 'px'}
`

Optionally pass a CSS property name as the second argument to enable property-specific defaults:

`javascript
// Absent units
units.parse(1, 'width'); // {'value': 1, 'unit': 'px'}
units.parse(1, 'opacity'); // {'value': 1, 'unit': ''}
units.parse(1, 'rotate'); // {'value': 1, 'unit': 'deg'}

// Absent values
units.parse('', 'width'); // {'value': 0, 'unit': 'px'}
units.parse('', 'opacity'); // {'value': 1, 'unit': ''}
`

##### Transforms
transform should not be passed directly as the property name - instead specify a transform keyword (e.g. rotate).

$3

Convert a formatted CSS value to a different unit (see supported units). For example:

`javascript
units.convert('cm', '12px'); // 0.3175
`

##### Element
Conversions to/from %, ch, em, ex require an element be passed as the third argument. This should be the element to which the converted CSS value applies/will apply:

`javascript
units.convert('em', '16px', document.getElementById('some-element')); // 1em
`

##### Property
Conversions to/from % require a CSS property name (e.g. _width_) be passed as the fourth argument. This should be the matching property name for the converted CSS value:

`javascript
units.convert('%', '16px', document.getElementById('some-element'), 'translateX'); // 10%
`

##### Transforms
transform should not be passed directly as the property name - instead specify a transform keyword (e.g. rotate).

$3

Get a default numeric value for a CSS property:

`javascript
units.getDefaultValue('opacity'); // 1
units.getDefaultValue('scale'); // 1
units.getDefaultValue('scale3d'); // 1
units.getDefaultValue('scaleX'); // 1
units.getDefaultValue('scaleY'); // 1
units.getDefaultValue('scaleZ'); // 1
units.getDefaultValue('lineHeight'); // 1
`

All other properties will return 0, for example:

`javascript
units.getDefaultValue('width'); // 0
`

$3

Get a default unit for a CSS property:

`javascript
units.getDefaultUnit('opacity'); // ''
units.getDefaultUnit('rotate'); // 'deg'
units.getDefaultUnit('rotate3d'); // 'deg'
units.getDefaultUnit('rotateX'); // 'deg'
units.getDefaultUnit('rotateY'); // 'deg'
units.getDefaultUnit('rotateZ'); // 'deg'
units.getDefaultUnit('skew'); // 'deg'
units.getDefaultUnit('skewX'); // 'deg'
units.getDefaultUnit('skewY'); // 'deg'
units.getDefaultUnit('scale'); // ''
units.getDefaultUnit('scale3d'); // ''
units.getDefaultUnit('scaleX'); // ''
units.getDefaultUnit('scaleY'); // ''
units.getDefaultUnit('scaleZ'); // ''
units.getDefaultUnit('lineHeight'); // ''
`

All other properties will return 'px', for example:

`javascript
units.getDefaultUnit('width'); // 'px'
`

Environment

Server-side use is supported, though converting to/from the following units requires a browser environment: %, ch, em, ex, rem, vh, vmax, vmin, vw.

Development

1. Clone repo and npm install
2. Make changes and ensure linting (gulp lint) & tests (gulp test) pass (combined task: gulp dev)
3. Create distributable files (gulp dist) - combined dev + dist task: gulp

Use gulp watch to run linter and tests on each file change (equivalent to manually running gulp dev`).