JavaScript--原型鏈

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原型鏈一.建構函式與原型鏈的關係

部落格中：http://www.cnblogs.com/shuiyi/p/5305435.html

的圖

 

 

 

例子：

 1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4     <meta charset="UTF-8"> 5     <title>Title</title> 6     <script> 7         function Person(obj) { 8             this.obj = obj || {} 9             this.name = this.obj.name || "匿名";10             this.age = this.obj.age || 18;11             this.sex = this.obj.sex || "男";12         }13 14         Person.prototype.fn = function () {15             console.log("我是掛載在原型鏈上的函數");16         }17         var p1 = new Person({18             name:"小明"19         });20 //        console.log(p1.__proto__.sayHi === p1.sayHi);// ture21         console.log("建構函式");22         console.dir(Person);23         console.log("執行個體化後的對象");24         console.dir(p1);25         console.log(Person.prototype === p1.__proto__); // true26         console.log(Person instanceof Object); //true27 28     </script>29 </head>30 <body>31 32 </body>33 </html>

Person.prototype === p1.__proto__ 以及Person instanceof Object是true的原因：

 二.原型指向

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title>Title</title>    <script>        // 萬物皆對象        function Person(name,age) {            this.name = name || "名字";            this.age = age ||18;        }        function Stuent(number) {//            this.name = name;//            this.age =age;            this.number = number;        }        // 修改指向方法一：推薦        Stuent.prototype = new Person();//        var stu1 = new Stuent("一號");        // 修改指向方法二：//        Stuent.prototype = {//            constructor:Person,//            age:11//        };        console.dir(Stuent);//        console.dir(stu1.age);    </script></head><body></body></html>

三.JS內建對象的原型鏈

 1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4     <meta charset="UTF-8"> 5     <script> 6         //        new Object(); 7         //        new Number(); 8         //        new String(); 9         //        new Boolean();10         //        new Function();11         //        new Date();12 13         //        var obj1 = new Object();14         //        var obj2 = {};15         //        console.dir(obj1);16         //        console.dir(obj2);17         //18         //        console.log(obj1 instanceof Object); // true19         //        console.log(obj2 instanceof Object);　// true20 21         var data1 = new Number("123");22         console.dir(data1);23         console.log(data1.__proto__); // Number24         console.log(data1.__proto__.__proto__); // Object25         console.log(data1.__proto__.__proto__.__proto__); // null26         console.log(data1.__proto__.__proto__ === data1.__proto__.__proto__); // ture27         //        console.dir(typeof  data1.toString()); //"123" string28 29         var data2 = true;30         // console.log(data2.toString()); // "true"31 32     </script>33     <title>Title</title>34 </head>35 <body>36 37 </body>38 </html>

 

JavaScript--原型鏈