js设计模式之状态模式

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>状态模式</title>
</head>
<body>
<button id="btn">开关</button>
<script>
    class OfflightState{
         constructor(light) {
             this.light = light;
         }
         //每个类都需要的这个方法，在不同的状态下按需要触发这个方法
        pressBtn(){
             this.light.setState(this.light.weekLightState);
            console.log("打开弱光")
        }
    }
    class WeekLightState{
        constructor(light) {
            this.light = light;
        }
        pressBtn(){
            this.light.setState(this.light.strongLightState);
            console.log("打开强光")
        }
    }
    class StrongLightState{
        constructor(light) {
            this.light = light;
        }
        pressBtn(){
            this.light.setState(this.light.offlightState);
            console.log("关闭灯光")
        }
    }
    class Light{
        constructor() {
            this.offlightState = new OfflightState(this);
            this.weekLightState = new WeekLightState(this);
            this.strongLightState = new StrongLightState(this);
            this.currentState = null;
        }
        setState(newState){
            this.currentState = newState;
        }
        init(){
            this.currentState=this.offlightState;
        }
    }
    let light = new Light();
    light.init();
    let btn = document.querySelector("#btn");
    btn.onclick=()=>{
        light.currentState.pressBtn();
    }
</script>
</body>
</html>