css-priority

calculate priority of css selector/rule

priority

We use Array(6) to store the priority value:

// rank algorithm
// -----------------
// a. important mark
// b. style attribte
// c. ID attribute (size)
// d. attributes + pseudo-class (size)
// e. element + pseudo-element (size)
// f. position of selector
var priority = [a, b, c, d, e, f]

Usage

calculate priority of selector (with rule info):

var priority = require('css-priority')

// output: [0, 0, 0, 0, 0, 12]
priority.parse('*', {
  line: 12
})

// output: [1, 0, 0, 2, 3, 88]
priority.parse('button.button > i.icon:before', {
  important: true,
  line: 88
})

Compare selectors:

var priority = require('css-priority')
 
var selectors = [
  '*'
  'li'
  'li:first-line'
  'ul li'
  'ul ol + li'
  'h1 + *[rel=up]'
  'ul ol li.red'
  'li.red.level'
]
var cache = {}
 
selectors.sort(function (a, b) {
  var calcA = cache[a] || (cache[a] = priority.parse(a))
  var calcB = cache[b] || (cache[b] = priority.parse(b))
 
  return priority.compare(a, b)
})

API

priority.parse(selector, opts)

• selector: {String} css selector
• opts: {Object} rule info
  • opts.important: {Boolean} important mark
  • opts.line: {Number} line number

parse css selector with rule info, and return Array(6) of priority

priority.compare(array1, array2)

• array1: {Array}
• array2: {Array}

Compare different priority array

LICENSE

MIT