JavaScript 实现京东风格密码显示与隐藏功能

<!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>
 <style>
  .box {
   position: relative;
   width: 400px;
   border-bottom: 1px solid #ccc;
   margin: 100px auto;
  }
  
  .box input {
   width: 370px;
   height: 30px;
   border: 0;
   outline: none;
  }
  
  .box img {
   position: absolute;
   top: 2px;
   right: 2px;
   width: 24px;
  }
 </style>
</head>
 
<body>
 <div class="box">
  <label for="">
   <img src="images/close.png" alt="" id="eye">
  </label>
  <input type="password" name="" id="pwd">
 </div>
 <script>
  // 1. 获取元素
  var eye = document.getElementById('eye');
  var pwd = document.getElementById('pwd');
  // 2. 注册事件 处理程序
  var flag = 0;
  eye.onclick = function() {
   // 点击一次之后， flag 一定要变化
   if (flag == 0) {
    pwd.type = 'text';
    eye.src = 'images/open.png';
    flag = 1; // 赋值操作
   } else {
    pwd.type = 'password';
    eye.src = 'images/close.png';
    flag = 0;
   }
 
  }
 </script>
</body>
 
</html>