<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> </head> <body> <script type="text/javascript"> function Person(myName, myAge) { // let per = new Object(); // let this = per; // this = stu; this.name = myName; // stu.name = myName; this.age = myAge; // stu.age = myAge; // return this; } Person.prototype.say = function () { console.log(this.name, this.age); } function Student(myName, myAge, myScore) { Person.call(this, myName, myAge); this.score = myScore; this.study = function () { console.log("day day up"); } } /*
弊端:
1.由于修改了Person原型对象的constructor属性, 所以破坏了Person的三角恋关系
2.由于Person和Student的原型对象是同一个, 所以给Student的元素添加方法, Person也会新增方法
*/ // Student.prototype = Person.prototype; Student.prototype = new Person();// Student.prototype.constructor = Student; Student.prototype.run = function(){ console.log("run"); } let per = new Person(); per.run(); /*
1.js中继承的终极方法
1.1在子类的构造函数中通过call借助父类的构造函数
1.2将子类的原型对象修改为父类的实例对象
*/ // let stu = new Student("ww", 19, 99); // console.log(stu.score); // stu.say(); // stu.study(); </script> </body> </html>
JS继承4
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