js復(fù)制一個(gè)對(duì)象用到了那些知識(shí)？

js復(fù)制一個(gè)對(duì)象用到了那些知識(shí),大神們給我點(diǎn)指示被唄？

var cloneObj = function (obj) {  
    var newObj = {};  
    if (obj instanceof Array) {  
        newObj = [];  
    }  
    for (var key in obj) {  
        var val = obj[key];  
        
        newObj[key] = typeof val === 'object' ? cloneObj(val): val;  
    }  
    return newObj;  
};  
//測(cè)試    
var obj = {a:function(){console.log(this.b.c)},b:{c:1}},  
newObj = cloneObj(obj); 
newObj.b.c=2;
obj.a();//1
newObj.a();//2