js拖拽

（1）原生js实现checkbox全选

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
    <div class="box" style="width:80px;">
      <p><label for="all">全选<input type="checkbox" id="all"></label></p>
      <p>西红柿<input type="checkbox" name="vegetable"></p>
      <p>黄瓜<input type="checkbox" name="vegetable"></p>
      <p>茄子<input type="checkbox" name="vegetable"></p>
    </div>

    <script>
    var all = document.getElementById('all');
    
    all.addEventListener("click",function(){
        var opts = document.getElementsByName('vegetable');
      for(var i = 0;i < opts.length;i++){
        opts[i].checked = this.checked;
      }
    },false)
    </script>
</body>
</html>