第188天：extend拷贝创建对象的原理

一、拷贝创建对象的原理

 //拷贝创建对象核心代码
    function extend(target,source) {
        //遍历对象
        for(var i in source){
            target[i] = source[i];
        }
        return target;
    }

    //游戏随机生成名字
       var boy = {
        name:'无忌'
        ,image:'男性头像'
        ,age:20
        ,sex:'男'
    };

    var gril = {
        name:'风晴雪'
        ,age:18
        ,image:'女性头像'
        ,sex:'女'
    };


    var zuixiake = extend({}, boy);
    zuixiake.name='醉侠客';
    console.log(zuixiake.name);//醉侠客
    console.log(zuixiake.sex);//男

二、拷贝进阶用法

<script>

    //extend2实现的功能：extend(target,obj1,obj2,obj3)

   function extend () {
        var key,i = 0,len = arguments.length,target = null,copy;
        if(len === 0){
            return;
        }else if(len === 1){
            target = this;
        }else{
            i++;
            target = arguments[0];
        }
        for(; i < len; i++){
            for(key in arguments[i]){
                copy = arguments[i][key];
                target[key] = copy;
            }
        }
        return target;
    }

    function extend2(){
        for (var p in source) {
            if (source.hasOwnProperty(p)) {
                target[p] = source[p];
            }
        }

        return target;
    }

    //游戏随机生成名字
    var boy = {
        name:'无忌'
        ,image:'男性头像'
        ,age:20
        ,sex:'男'
    };

    //技能名称，等级，伤害值，需要的魔法
    var technology = {tname:'亡灵复活',tlevel:10,tstrength:3000,tmagic:30};

    var shenqi = {sname:'霜之哀伤',slevel:30,sstrength:3000};
    //当这个人有了穿上盔甲，圣衣，六神合体，戴上魔法戒指之后，自动也拥有一个技能

    //第一种用法
    var zuixiake = extend({}, technology,shenqi);
    zuixiake.name='醉侠客';
    console.log(zuixiake.name);//醉侠客
    console.log(zuixiake.tname);//亡灵复活
    console.log(zuixiake.sname);//霜之哀伤


    //第二种用法
    extend(boy,technology,shenqi);
    console.log(boy.name);//无忌
    console.log(boy.tname);//亡灵复活
    console.log(boy.sname);//霜之哀伤

</script>