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;
this.say = function () { // stu.say = function () {}
console.log(this.name, this.age);
}
// return this;
}
function Student(myName, myAge, myScore) {
// let stu = new Object();
// let this = stu;
// 通过call修改this和传参
Person.call(this, myName, myAge); // Person.call(stu);
this.score = myScore;
this.study = function () {
console.log("day day up");
}
// return this;
}
let stu = new Student("ww", 19, 99);
console.log(stu.score); // 99
stu.say(); // ww 19
stu.study(); // day day up
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继承方式二的弊端
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如果动态的给Person的原型对象添加一个方法, 那么使用继承方式二就不能在子对象中访问say方法
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; } // 如果将say方法放到Person原型对象中, 那么用继承方式二将不能访问say, 这就是继承方式二的弊端 Person.prototype.say = function () { console.log(this.name, this.age); } function Student(myName, myAge, myScore) { // let stu = new Object(); // let this = stu; Person.call(this, myName, myAge); // Person.call(stu); this.score = myScore; this.study = function () { console.log("day day up"); } // return this; } let stu = new Student("ww", 19, 99); console.log(stu.score); stu.say(); // 报错 stu.study();报错的原因
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