javascript中in和hasOwnProperty區別

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in操作符只要通過對象能訪問到屬性就返回true。hasOwnProperty()只在屬性存在於執行個體中時才返回true。

function Person(){}Person.prototype.name = "Nicholas";Person.prototype.age = 29;Person.prototype.job = "Software Engineer";Person.prototype.sayName = function(){    alert(this.name);};var person1 = new Person();var person2 = new Person();alert(person1.hasOwnProperty("name"));//falsealert("name" in person1);//trueperson1.name = "Greg";alert(person1.name);//"Greg"alert(person1.hasOwnProperty("name"));//truealert("name" in person1);//truedelete person1.name;alert(person1.name);//"Nicholas"alert(person1.hasOwnProperty("name"));//falsealert("name" in person1);//true

 

javascript中in和hasOwnProperty區別