lovecoding
/
VIP30


			
				
					
						
						
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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>Document</title>
  <style>
    img {
      position: absolute;
    }
  </style>
</head>

<body>
  <!-- <img src="./img/1.png" alt=""> -->
  <script>

    //获取屏幕宽度和高度
    var screenWidth = document.body.clientWidth || document.documentElement.clientWidth
    var screenHeight = document.body.clientHeight || document.documentElement.clientHeight
    //构造函数  写属性
    function leaf() {
      //图片宽度
      this.width = 100 + 100 * Math.random()
      //图片位置
      this.xLeft = (screenWidth - this.width) * Math.random()
      //距离顶部
      this.xTop = 0
      //图片路径
      //<img src="./img/1.png" alt="">
      /* 
      Math.random()         (0-1)
      Math.random() * 4     (0-4)
      Math.random() * 4 + 1 (1-5)
      Math.floor(Math.random() * 4 + 1) [1,2,3,4]
      */
      this.bg = 'img/' + Math.floor(Math.random() * 4 + 1) + '.png'
    }
    //原型对象下面写方法
    leaf.prototype.init = function () {
      //创建img标签
      var oImg = document.createElement('img')
      //赋值属性
      oImg.src = this.bg
      oImg.style.width = this.width + 'px'
      oImg.style.left = this.xLeft + 'px'
      oImg.style.top = this.xTop + 'px'
      document.body.appendChild(oImg)
      this.img = oImg
    }
    //下落的方法
    leaf.prototype.fall = function () {
      // console.log(this) //leaf
      setTimeout(function () {
        // console.log(this)//leaf
        this.timer = setInterval(function () {
          // console.log(this)
          if (this.img.offsetTop < screenHeight - this.img.offsetHeight) {
            this.img.style.top = this.img.offsetTop + 10 + 'px'
          } else {
            clearInterval(this.timer)
          }
        }.bind(this), 20)
      }.bind(this), Math.random() * 2000)
    }

    var leafArr = []
    for (var i = 0; i < 20; i++) {
      //创建实例化对象
      var leaf1 = new leaf()
      leafArr.push(leaf1)
      leaf1.init()
    }

    document.onclick = function () {
      for (var i = 0; i < leafArr.length; i++) {
        leafArr[i].fall()
      }
    }
  </script>
</body>

</html>