多态
个人笔记，方便自己看，另外感谢后盾人向军老师。本笔记是通过观看向军老师视频得出。
根据多种不同的形态产生不同的结果就是多态
function User() { };
User.prototype.show = function () {
this.description();
}
function User1() { };
User1.prototype = Object.create(User.prototype);
User1.prototype.description = function () {
console.log('User1');
}
function User2() { };
User2.prototype = Object.create(User.prototype);
User2.prototype.description = function () {
console.log('User2');
}
function User3() { };
User3.prototype = Object.create(User.prototype);
User3.prototype.description = function () {
console.log('User3');
}
for (const a of [new User1, new User2, new User3]) {
a.show();//User1
//User2
//User3
}
同一个函数的执行，产生三个不同的结果
利用父类构造函数初始化属性
function User(name, age) {
this.name = name;
this.age = age;
};
User.prototype.show = function () {
console.log(this.name, this.age);
}
function User1(name, age) {
User.call(this, name, age);
}
User1.prototype = Object.create(User.prototype);
let why = new User1('why', 19);
why.show()
function User2(...args) {
User.apply(this, args);
}
User2.prototype = Object.create(User.prototype);
let wy = new User2('wy', 18);
wy.show()
// 封装一个extend函数，用于子函数继承父函数
function extend(child, parent) {
child.prototype = Object.create(parent.prototype);
child.prototype.constructor = child;
Object.defineProperty(child.prototype, 'constructor', {
value: child,
enumerable: false,
})
}
对象工厂派生对象并实现继承
function User(name, age, sex) {
this.name = name;
this.age = age;
this.sex = sex;
};
User.prototype.show = function () {
console.log(this.name, this.age);
}
function User1(name, age, sex) {
const stance = Object.create(User.prototype);
User.call(stance, name, age, sex);
stance.Issex = function () {
console.log(this.sex === 'man' ? 'man' : 'woman');
}
return stance;
}
let why = new User1('why', 19, 'man');
console.dir(why)
why.show(); //why,19
why.Issex(); // man
多继承Object.assgin()
function User(name, age = 19) {
this.name = name;
this.age = age;
};
User.prototype.show = function () {
console.log(this.name, this.age);
}
let User1 = {
sayOne() {
console.log('there is One,your name is ' + this.name);
}
}
let User2 = {
sayTwo() {
console.log('there is Two,your name is ' + this.name);
}
}
let User3 = {
sayThree() {
console.log('there is Three,your name is ' + this.name);
}
}
function Customer(name) {
let constance = Object.create(User.prototype);
User.call(constance, name)
return constance;
}
// 如果实例想使用sayOne，可以将将sayOne函数设为User的原型，但使用不同对象的方法越多，继承就更为混乱，所以
// 多继承使用属性合并，将构造函数改为对象。
Customer.prototype = Object.assign(User.prototype, User1, User2, User3)
let wy = new Customer('wy', 18);
wy.sayOne() //there is One,your name is wy
wy.sayThree() //there is Three,your name is wy
wy.show() //wy 19
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