vendor-prefix/index.js

vendor prefix css attributes

'use strict';

var style = document.createElement('p').style,
    prefixes = 'O ms Moz webkit'.split(' '),
    hasPrefix = /^(o|ms|moz|webkit)/,
    upper = /([A-Z])/g,
    memo = {};

function get(key){
    return (key in memo) ? memo[key] : memo[key] = prefix(key);
}

function prefix(key){
    var capitalizedKey = key.replace(/-([a-z])/g, function(s, match){
            return match.toUpperCase();
        }),
        i = prefixes.length,
        name;

    if (style[capitalizedKey] !== undefined) return capitalizedKey;

    capitalizedKey = capitalize(key);

    while (i--) {
        name = prefixes[i] + capitalizedKey;
        if (style[name] !== undefined) return name;
    }

    throw new Error('unable to prefix ' + key);
}

function capitalize(str){
    return str.charAt(0).toUpperCase() + str.slice(1);
}

function dashedPrefix(key){
    var prefixedKey = get(key),
        upper = /([A-Z])/g;

    if (upper.test(prefixedKey)) {
        prefixedKey = (hasPrefix.test(prefixedKey) ? '-' : '') + prefixedKey.replace(upper, '-$1');
    }

    return prefixedKey.toLowerCase();
}

module.exports = get;
module.exports.dash = dashedPrefix;