js实现翻牌小游戏

* {
  margin: 0;
  padding: 0;
 }

 body,
 html {
  height: 100%;
 }

 .wrap {
  perspective: 1000px;
  width: 320px;
  height: 320px;
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  margin: auto;
  display: flex;
  justify-content: center;
  text-align: center;
  flex-wrap: wrap;
 }

 .wrap div {
  /* box-shadow: 5px 5px 10px #000; */
  transition: 1s;
  position: relative;
  text-align: center;
  line-height: 60px;
  height: 60px;
  width: 60px;
  border-radius: 10px;

  margin: 10px 10px;
 }

 .wrap div .active1 {
  transform: rotateY(180deg);
 }

 .wrap div .active2 {
  transform: rotateY(360deg);
 }

 .wrap p {
  border-radius: 10px;
  background-color: blueviolet;
  transition: 1s;
  backface-visibility: hidden;
  display: block;
  height: 60px;
  width: 60px;
  position: absolute;
  /* transform: rotateY(180deg); */
 }

 .wrap .bottom {
  transform: rotateY(180deg);
 }
 h3{
  text-align: center;
  width: 200px;
  height: 30px;
  margin: 150px auto;
 }

class Game {
  constructor(selector) {
  this.init(selector);
  }
  init(selector) {
  let arr = this.randomArr();
  this.nodes = [...document.querySelectorAll(selector)];//获取每一个卡片
  this.step = 50;//定义可以被点击的次数
  this.tit = document.querySelector("h3");
  this.nodes.forEach((item,index) => {//初始化卡片的值，并保存在num属性中
   item.children[1].innerHTML = arr[index];
   item.num = arr[index];
   var that = this
   item.Onclick= function () {//给每一个卡片绑定事件
   that.handle(this);
   }
  })
  }
  handle(ele) {
  if(this.step === 0){
   alert('游戏结束')
   return
  }
  if(ele.active !== true){
   this.step--;
   this.tit.innerText = `剩余步数：${this.step}`
  }
  ele.children[0].classList.add('active1');//卡片翻转
  ele.children[1].classList.add('active2'); 
  let res = this.nodes.filter(item => item.children[0].classList.contains('active1')&& item.active !== true); //获取翻过来的且没有配对成功的卡片
  if(res.length === 2 && res[0].num !== res[1].num){//如果有两张并且数值不相等，恢复原状 
   setTimeout(()=>{
   res[0].children[0].classList.remove('active1');
   res[0].children[1].classList.remove('active2');
   res[1].children[0].classList.remove('active1');
   res[1].children[1].classList.remove('active2'); 
   },1000)//延迟一秒形成动画 
  }else if(res.length === 2 && res[0].num === res[1].num){//如果数值相等则配对成功
   res[0].active = true;//锁定卡片
   res[1].active = true;
  }
  }
  randomArr() {
  let arr = [];
  for (let i = 0, n = 8; i