深度扩展函数，来自jquery

extendDeep.js

function extendDeep() {
        var target = arguments[0] || {};
        var arrs = slice.call(arguments, 1);
        var len = arrs.length;
        var copyIsArr;

        for (var i = 0; i < len; i++) {
            var arr = arrs[i];
            for (var name in arr) {
                var src = target[name];
                var copy = arr[name];
                
                //避免无限循环
                if (target === copy) {
                    continue;
                }
                
                if (copy && (isObj(copy) || (copyIsArr = isArr(copy)))) {
                    if (copyIsArr) {
                        copyIsArr = false;
                        var clone = src && isArr(src) ? src : [];

                    } else {
                        var clone = src && isObj(src) ? src : {};
                    }
                    target[ name ] = extendDeep(clone, copy);
                } else if (typeof copy !== 'undefined'){
                    target[name] = copy;
                }
            }

        }

        return target;
    }