1.对象的继承扩展——深度复制

Object.prototype.extend = function(...rest){
        //使用es6中的剩余参数方式来取代之前arguments
        var i=0,
            len = rest.length;
        for(i; i<len; i++){
            var source = rest[i];
            for(var property in source){
                //通过hasOwnProperty的判断来避免操作prototype上的属性
                if(source.hasOwnProperty(property)){
                    var sourceTmp = {};
                    if(typeof source[property] == "object"){
                        var tmp = Array.isArray(source[property]) ? [] : {};
                        sourceTmp = tmp.extend(source[property]);
                    } else {
                        sourceTmp = source[property];
                    }
                    this[property] = sourceTmp;
                }
            }
        }
    return this;
}