extends.ts
class E {
constructor(private name: string, private age: number) {
}
sayHello() {}
}
class F extends E {
constructor(name: string, age: number, private score: number) {
super(name, age)
}
sayHello() {}
sayGoodbye(){}
}
let f = new F('Rick.Xu', 33, 100)
let e = new E('Ashley', 23);
extends.js
var __extends = (this && this.__extends) || (function () {
var extendStatics = function (d, b) {
extendStatics = Object.setPrototypeOf ||
({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
function (d, b) { for (var p in b) if (Object.prototype.hasOwnProperty.call(b, p)) d[p] = b[p]; };
return extendStatics(d, b);
};
return function (d, b) {
extendStatics(d, b);
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
// test by Rick
console.log(__.prototype == b.prototype) // true
console.log(d.prototype instanceof __) // true
var a = new __()
a.sayHello()
// a.sayGoodbye() // a.sayGoodbye is not a function
// test by Rick end
};
})();
var E = /** @class */ (function () {
function E(name, age) {
this.name = name;
this.age = age;
}
E.prototype.sayHello = function () { };
return E;
}());
var F = /** @class */ (function (_super) {
__extends(F, _super);
function F(name, age, score) {
var _this = _super.call(this, name, age) || this;
_this.score = score;
return _this;
}
F.prototype.sayHello = function () { };
F.prototype.sayGoodbye = function () { };
return F;
}(E));
var f = new F('Rick.Xu', 33, 100);
var e = new E('Ashley', 23);
typescript 编译后成 ES3后，原型链中加了一个中间对象 __ 。子类的原型对象是 __，__的原型对象是父类的原型对象。和下面的方法等效：
d.prototype = Object.create(b.prototype);