to-style/prefixInfo.js

Convert style objects to style strings

'use strict'

var toUpperFirst = require('ustring').toUpperFirst
var re         = /^(Moz|Webkit|Khtml|O|ms|Icab)(?=[A-Z])/

var docStyle   = typeof document == 'undefined'?
                    {}:
                    document.documentElement.style

var prefixInfo = (function(){

    var prefix = (function(){

            for (var prop in docStyle) {
                if( re.test(prop) ) {
                    // test is faster than match, so it's better to perform
                    // that on the lot and match only when necessary
                    return  prop.match(re)[0]
                }
            }

            // Nothing found so far? Webkit does not enumerate over the CSS properties of the style object.
            // However (prop in style) returns the correct value, so we'll have to test for
            // the precence of a specific property
            if ('WebkitOpacity' in docStyle){
                return 'Webkit'
            }

            if ('KhtmlOpacity' in docStyle) {
                return 'Khtml'
            }

            return ''
        })(),

    lower = prefix.toLowerCase()

    return {
        style       : prefix,
        css       : '-' + lower + '-',
        dom       : ({
            Webkit: 'WebKit',
            ms    : 'MS',
            o     : 'WebKit'
        })[prefix] || toUpperFirst(prefix)
    }

})()

module.exports = prefixInfo