if三目简写 左边无效

Question

<script>
    function Clone(obj){
        for (var key in obj )
        {
            this[key]=(typeof obj[key]="object")?new Clone(obj[key]):obj[key];
        };

    };
    function Person(name,age,marry,sex){
        this.name=name;
        this.age=age;
        this.marry=marry;
        this.sex=sex;
    };
    Person.prototype.showName=function(){
        alert(this.name);
    };

    function PersonChild(pArr,weight){
        Person.apply(pArr,this);
        this weight=weight;
    };
    
    PersonChild.prototype=new Clone(Person.prototype);
    PersonChild.prototype.showAge=function(){
        alert (this.age);
    };

    alert(Person.prototype.showAge);
  </script>

this[key]=(typeof obj[key]="object")?new Clone(obj[key]):obj[key];
这串代码，左边无效是为什么

Answer 1

typeof obj[key]="object"
少了等于号
=== 严格相等
== 宽松相等
= 赋值