typescript继承 __extends = (this && this.__extends) || (function () { 代码解读

 　　　// function (d, b) 参数d子函数,b父函数. 
　　　// (this && this.__extends)防止this.extends取到空类型, 如果this类型为空, 不执行this.__extends.
 1 　　var __extends = (this && this.__extends) || (function () {
    var extendStatics = function (d, b) {
        extendStatics = Object.setPrototypeOf ||
　　　　　　　　　// 设置__proto__
            ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
　　　　　　　　　//拷贝静态属性
            function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
        return extendStatics(d, b);
    };
    return function (d, b) {
　　　　　　// 拷贝静态属性
        extendStatics(d, b);
　　　　　　//拷贝静态函数
        function __() { this.constructor = d; }
　　　　　　//设置原型
        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
    };
})();

TS源文件:

class Shape {
 
    area: number;
    color: string;
    text: string;
 
    constructor (public name: string,  number, height: number ) {
        this.area = width * height;
        this.color = "pink";
        this.text = 'I am a 2D object:';
    };
 
    shoutout() {
        return this.text + this.color + " " + this.name +  " with an area of " + this.area + " cm squared.";
    }
}

class Shape3D extends Shape {
 
    volume: number;
    
 
    constructor ( public name: string,  number, height: number, length: number ) {
        super( name, width, height );
        this.volume = length * this.area;
        this.text = 'I am a 3D object:';
    };
 
    shoutout() {
        return this.text + this.name +  " with a volume of " + this.volume + " cm cube.";
    }
 
    superShout() {
        return super.shoutout();
    }
}

class Shape4D extends Shape3D {
    
    d4volume: number;
    constructor ( public name: string,  number, height: number, length: number, d4: number ){
        super(name, width, height, length);
        this.d4volume = d4 * this.volume;
        this.text = 'I am a 4D object';
    };
    
    shoutout() {
        return this.text + this.name +  " with a d4volume of " + this.d4volume + " cm d4cube.";
    }
    
    superShout(){
        return super.shoutout();
    }
}

var cube = new Shape3D("cube", 30, 30, 30);
console.log( cube.shoutout() );
console.log( cube.superShout());

var d4cube = new Shape4D("d4cube", 30, 30, 30, 30);
console.log( d4cube.shoutout() );
console.log( d4cube.superShout() );

js编译后的文件:

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 (b.hasOwnProperty(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 __());
    };
})();
var Shape = /** @class */ (function () {
    function Shape(name, width, height) {
        this.name = name;
        this.area = width * height;
        this.color = "pink";
        this.text = 'I am a 2D object:';
    }
    ;
    Shape.prototype.shoutout = function () {
        return this.text + this.color + " " + this.name + " with an area of " + this.area + " cm squared.";
    };
    return Shape;
}());
var Shape3D = /** @class */ (function (_super) {
    __extends(Shape3D, _super);
    function Shape3D(name, width, height, length) {
        var _this = _super.call(this, name, width, height) || this;
        _this.name = name;
        _this.volume = length * _this.area;
        _this.text = 'I am a 3D object:';
        return _this;
    }
    ;
    Shape3D.prototype.shoutout = function () {
        return this.text + this.name + " with a volume of " + this.volume + " cm cube.";
    };
    Shape3D.prototype.superShout = function () {
        return _super.prototype.shoutout.call(this);
    };
    return Shape3D;
}(Shape));
var Shape4D = /** @class */ (function (_super) {
    __extends(Shape4D, _super);
    function Shape4D(name, width, height, length, d4) {
        var _this = _super.call(this, name, width, height, length) || this;
        _this.name = name;
        _this.d4volume = d4 * _this.volume;
        _this.text = 'I am a 4D object';
        return _this;
    }
    ;
    Shape4D.prototype.shoutout = function () {
        return this.text + this.name + " with a d4volume of " + this.d4volume + " cm d4cube.";
    };
    Shape4D.prototype.superShout = function () {
        return _super.prototype.shoutout.call(this);
    };
    return Shape4D;
}(Shape3D));
var cube = new Shape3D("cube", 30, 30, 30);
console.log(cube.shoutout());
console.log(cube.superShout());
var d4cube = new Shape4D("d4cube", 30, 30, 30, 30);
console.log(d4cube.shoutout());
console.log(d4cube.superShout());