【Html】交通灯问题-编程知识

【Html】交通灯问题

效果

在这里插入图片描述

实现方式

计时器：setTimeout或setInterval来计时。setInterval和 setTimeout 在某些情况下可能会出现计时不准确的情况。这通常是由于JavaScript的事件循环机制和其他代码执行所需的时间造成的。
问询：通过getCurrentLight将每个状态的持续时间设置为精确的值，并使用requestAnimationFrame来递归调用getCurrentLight函数，我们可以更准确地控制交通灯的状态。

源码

index.html

<!DOCTYPE html>
<html><head><title>交通灯</title><link type="text/css" rel="styleSheet" href="./index.css" /></head><body><div class="traffic-light"><div class="traffic-container"><div class="light green"></div><div class="light yellow"></div><div class="light red"></div></div><div class="time">90</div></div><script type="module">import {TrafficLight} from './TrafficLight.js';const time = document.querySelector('.time');const trafficDom = document.querySelector('.traffic-light');const light = new TrafficLight({red:3,yellow:2,green:5,initial:'red',});function raf(){requestAnimationFrame(()=>{raf();const current = light.getCurrentLight();time.textContent =current.remain;trafficDom.className = `traffic-light ${current.color}`;console.log(current.color,current.remain);})}raf();</script></body>
</html>

index.css

* {margin: 0;padding: 0;box-sizing: border-box;
}body{width: 100vw;height: 100vh;margin: 0;/* backgroud: #191c29 */background: #fff;
}.traffic-light{width: 200px;margin: 10px auto;-webkit-box-flex: inherit;text-align: center;
}.light{width: 20px;height: 20px;border-radius: 10px;display:inline-block;background-color: gray;margin: 10px auto;
}.red .red{background-color: red;
}.green .green{background-color: green;
}
.yellow .yellow{background-color: yellow;
}.time{font-family: 'DS-Digital';font-size: 40px;
}

TrafficLight.js

export class TrafficLight {constructor(options) {const {red = 60,green = 60,yellow = 3,initial = 'green',} = options || {};this._colors ={red:{seconds: red,next:'yellow',},green:{seconds: green,next:'yellow',},yellow:{seconds : yellow,},};this._switch(initial);}_switch(color){this._currentColor = color;this._seconds = this._colors[color].seconds;this._time = Date.now();}_next(){if(this._currentColor === 'red'){this._colors.yellow.next = 'green';}  else if(this._currentColor === 'green'){this._colors.yellow.next = 'red';} else{}this._switch(this._colors[this._currentColor].next);
}getCurrentLight(){const remain = Math.ceil(this._seconds -(Date.now() - this._time)/1000);if(remain<=0){this._next();return this.getCurrentLight();}return {color: this._currentColor,remain,};}}