设计模式 装饰器模式

class Circle {
    draw() {
        console.log(‘画一个圆形‘);
    }
}

class Decorator {
    constructor(circle) {
        this.circle = circle;
    }
    draw() {
        this.circle.draw();
        this.setRedBorder(circle);
    }
    setRedBorder(circle) {
        console.log(‘设置红色边框‘)
    }
}

// 测试
let circle = new Circle();

let client = new Decorator(circle);
client.draw();

{
    "presets": ["es2015", "latest"],
    "plugins": ["transform-decorators-legacy"]
}

// 一个简单的demo
@testDec
class Demo {
    // ...
}

function testDec(target) {
    target.isDec = true
}

alert(Demo.isDec)

// 装饰器原理
@decorator
class A {}

// 等同于
class A {}
A = decorator(A) || A;

@testDec(false)

class Demo {
}

function testDec(isDec) {
    return function (target) {
        target.isDec = isDec
    }
}

alert(Demo.isDec);

将现有对戏那个和装饰器进行分离，两者独立存在
符合开放封闭原则