关于javascript:状态模式

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title> 状态模式 </title>
</head>
<body>
    <script>
        // 状态父类
        class LightState {constructor(light) {this.light = light}

            buttonWasPressed() {throw new Error('父类的 buttonWasPressed 办法必须被重写')
            }
        }

        // 状态子类
        class OffLightState extends LightState {buttonWasPressed() {console.log('弱光') // offLightState 对应的行为
                this.light.setState(this.light.weakLightState) // 切换状态到 weakLightState
            }
        }

        class WeakLightState extends LightState {buttonWasPressed() {console.log('强光') // weakLightState 对应的行为
                this.light.setState(this.light.strongLightState) // 切换状态到 strongLightState
            }
        }

        class StrongLightState extends LightState {buttonWasPressed() {console.log('超强光') // strongLightState 对应的行为
                this.light.setState(this.light.superStrongLightState) // 切换状态到 superStrongLightState
            }
        }

        class SuperStrongLightState extends LightState {buttonWasPressed() {console.log('关灯') // superStrongLightState 对应的行为
                this.light.setState(this.light.offLightState) // 切换状态到 offLightState
            }
        }

        // 灯类
        class Light {constructor() {this.offLightState = new OffLightState(this)
                this.weakLightState = new WeakLightState(this)
                this.strongLightState = new StrongLightState(this)
                this.superStrongLightState = new SuperStrongLightState(this)
                this.button = null
            }

            init() {const button = document.createElement('button')
                this.button = document.body.appendChild(button)
                this.button.innerHTML = '开关'

                this.currState = this.offLightState // 设置以后状态
                this.button.onclick = () => this.currState.buttonWasPressed() // 将申请委托给以后的状态对象
            }

            setState(newState) {this.currState = newState}
        }

        const light = new Light()
        light.init()
    </script>
</body>
</html>

正文完