`path.resolve` for browser

resolvePath.js

var resolvePath = function () {
    function resolve(pathA, pathB) {
        // 先做split，得到的结果如下几种
        //  ‘a’     => ['a']
        //  'a/b'   => ['a', 'b']
        //  '/a/b'  => ['', 'a', 'b']
        //  '/a/b/' => ['', 'a', 'b', '']
        pathB = pathB.split('/');
        if (pathB[0] === '') {
            // 如果pathB是想对于根目录
            // 则不在考虑pathA，直接返回pathB
            return pathB.join('/');
        }
        pathA = pathA.split('/');
        var aLastIndex = pathA.length - 1;
        if (pathA[aLastIndex] !== '') {
            // 文件名出栈，只保留路径
            pathA[aLastIndex] = '';
        }

        var part;
        var i = 0;
        while (typeof(part = pathB[i]) === 'string') {
            switch (part) {
                case '..':
                    // 进入父级目录
                    pathA.pop();
                    pathA.pop();
                    pathA.push('');
                    break;
                case '.':
                    // 当前目录
                    break;
                default:
                    // 进入子目录
                    pathA.pop();
                    pathA.push(part);
                    pathA.push('');
                    break;
            }
            i++;
        }
        return pathA.join('/');
    }

    var paths = arguments;
    var i = 0;
    var path;
    var r = location.pathname;
    var multiSlashReg = /\/\/+/g;
    while (typeof(path = paths[i]) === 'string') {
        // '//' ==> '/'
        path = path.replace(multiSlashReg, '/');
        r = resolve(r, path);
        i++;
    }

    return r;
};