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>
</head>
<body>
  <button id="btn">按钮A</button>
  <button id="btnB">按钮B</button>
  <button id="stop">停止</button>
  <button id="btnC">按钮C</button>
  
  <script>
    var btn = document.getElementById('btn')
    var btnB = document.getElementById('btnB')
    var stop = document.getElementById('stop')
    var btnC = document.getElementById('btnC')
    btn.onclick = function(){
      var a = 1
      var b = setTimeout(function(){
        a++
        console.log(a)
      },1000)
    }

    btnB.onclick = function(){
      var a = 1
      var c = setInterval(function(){
        a++
        console.log(a)
      },1000)
      stop.onclick = function(){
        clearInterval(c)
      }
    }
    //setTimeout  只执行一次
    //setInterval  不断的执行


    btnC.onclick = function(){
      //实现随机数  0-1
      var a = Math.random() * 100
      //Math.floor() 向下取整 跟四舍五入没有关系
      console.log(Math.floor(a))
      
    }
  </script>
</body>
</html>