SOURCE

class AbstractBox {
    constructor() {
        console.log('Flyweight Class created');
    }

    getShape() {
        throw new Error("This method must be overwritten!");
    }

    display(color) {
        console.log("方块颜色：" + color);
    }
}

class BoxFactory {
    constructor() {
        console.log('FlyweightFactory Class created');
    }
    static getBox(key) {
        if(!this.flyweights[key]){
           switch (key) {
                case 'I':
                    this.flyweights[key] = new IBox();
                    break;
                case 'L':
                    this.flyweights[key] = new LBox();
                    break;
                case 'O':
                    this.flyweights[key] = new OBox();
                    break;
                default:
                    throw new Error("The Linux distribution you are looking for has not been found");
            }
        }
        return this.flyweights[key];
    }

    static createGibberish(){
        return new UnsharedBox();
    }
}
BoxFactory.flyweights = {};
class UnsharedBox extends AbstractBox {
    getShape() {
        console.log('我是不共享的享元对象')
    }
}
// I形方块
class IBox extends AbstractBox {
    getShape() {
        return "I";
    }
}

// L形方块
class LBox extends AbstractBox {
    getShape() {
        return "L";
    }
}

// O形方块
class OBox extends AbstractBox {
    getShape() {
        return "O";
    }
}

let i1 = BoxFactory.getBox("I");
console.log(111111)
i1.display('red');

let i2 = BoxFactory.getBox("L");
i2.display('blue');
let i3 = BoxFactory.getBox("O");
i3.display('green');
let i4 = BoxFactory.getBox("O");
i4.display('yellow');
// 也可以更改外观状态
i4.display('grey');
// 用 == 对比两个对象
console.log("两个对象是否相等：" + (i3 == i4));

// 对于非享元对象的调用
let unsharebox = BoxFactory.createGibberish();