to-style/prefixer.js

Convert style objects to style strings

var ustring = require('ustring')
var camelize = ustring.camelize
var hyphenate = ustring.hyphenate
var toLowerFirst = ustring.toLowerFirst
var toUpperFirst = ustring.toUpperFirst

var prefixInfo = require('./prefixInfo')
var prefixProperties = require('./prefixProperties')

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

module.exports = function(asStylePrefix){

    return function(name, config){
        config = config || {}

        var styleName = toLowerFirst(camelize(name)),
            cssName   = hyphenate(name),

            theName   = asStylePrefix?
                            styleName:
                            cssName,

            thePrefix = prefixInfo.style?
                            asStylePrefix?
                                prefixInfo.style:
                                prefixInfo.css
                            :
                            ''

        if ( styleName in docStyle ) {
            return config.asString?
                              theName :
                            [ theName ]
        }

        //not a valid style name, so we'll return the value with a prefix

        var upperCased     = theName,
            prefixProperty = prefixProperties[cssName],
            result         = []

        if (asStylePrefix){
            upperCased = toUpperFirst(theName)
        }

        if (typeof prefixProperty == 'function'){
            var prefixedCss = prefixProperty(theName, thePrefix) || []
            if (prefixedCss && !Array.isArray(prefixedCss)){
                prefixedCss = [prefixedCss]
            }

            if (prefixedCss.length){
                prefixedCss = prefixedCss.map(function(property){
                    return asStylePrefix?
                                toLowerFirst(camelize(property)):
                                hyphenate(property)

                })
            }

            result = result.concat(prefixedCss)
        }

        if (thePrefix){
            result.push(thePrefix + upperCased)
        }

        result.push(theName)

        if (config.asString || result.length == 1){
            return result[0]
        }

        return result
    }
}