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js determines whether the account password on the login interface is empty

高洛峰Original: 2017-02-11 17:23:502987browse

This article mainly introduces the method of using none and block of display to determine whether the account password of the login interface is empty. It has a very good reference value. Let’s take a look at it with the editor.

If you want to determine whether the account password on the login interface is empty and you don’t want to use the alert display, you need to use display to hide the alert (when setting it up) Do not write the hidden content in the p of the account number and password, otherwise it will change according to the screen resolution. This is my lesson)

First define the account number, password and the id of the hidden part , that is, var x=document.getElementById("id"), including the id of the button, and then when you click the login button (btn.onclick=function(){specific selection to hide and display content}), you need to write a function to select and hide and display; the reset button is (btn.onclick=function(){cleared content, including the content displayed by the login button})

The specific code is as follows:

<html xmlns="http://www.w3.org/1999/xhtml" lang="en">
<head>
<meta charset="UTF-8" />
<title>请登录</title><base target="_blank" /> 
<style>
 body{
 margin:0px auto;
 background-image: url(images/dlbj1.png) ;
 position: relative;
 }
 .dl{
 width: 380px ;
 height: 220px ;
 background-image: url(images/dl.png) ;
 text-align: center ;
 margin: auto ;
 margin-top: 15% ; 
 position: center; 
 } 
 .btn{
 font-family : 微软雅黑 ;
 font-size: medium ;
 }
 #username{
 max-width: 200px ;
 margin: 10px 0px 0px 0px ;
 height: 28px ;
 }
 #us{
 color: #FFFFFF ;
 font-family : 微软雅黑;
 }
 #ps{
 color: #FFFFFF ;
 font-family : 微软雅黑;
 }
 #password{
 max-width: 200px ; 
 margin: 20px 0px 10px 0px ;
 height: 28px ;
 }
</style>
</head>
<body>
 <form class="dl" method="post">
 <p class="dlsy">
  <br/><br/><br/>
  <p class="username">
  账号：<input type="text" id="username"/><span id="u" style="display: none;color: red;font-size:13px;">*请输入账号！</span>
  </p>
  <p class="password">
  密码：<input type="password" id="password"/><span id="p" style="display: none;color: red;font-size:13px;">*请输入密码！</span>
  </p>
  <p class="empty">
  <span id="up" style="display: none;color: red;font-size:13px;">*账号或密码错误</span>
  </p>
  <p class="btn">
  <button type="button" id="reset" class="btn btn-default button-rounded button-small">重置</button>            
  <button type="button" id="submit" class="btn btn-default button-rounded button-small">登录</button>
  </p>
 </p>
 </form> 

 <script type="text/javascript">
  var x=document.getElementById("username");
  var y=document.getElementById("password");
  var btnSubmit = document.getElementById("submit");
  var btnReset = document.getElementById("reset");
  var u=document.getElementById("u");
  var p=document.getElementById("p");
  var up=document.getElementById("up");
  //点击登录按钮时判断账号、密码是否为空或错误
  btnSubmit.onclick=function(form){
  if(x.value==""){
   if(y.value==""){
   up.style.display="block";
   }
   else{
   u.style.display="block";
   up.style.display="none";
   }
   }
  else if(y.value==""){
   if(x.value==""){
   up.style.display="block";
   }
   else{
   p.style.display="block";
   up.style.display="none";
   }
  }
  else{
   u.style.display="none";
   up.style.display="block";
   p.style.display="none";
  }
  }
  //点击重置按钮时清空账号密码
  btnReset.onclick=function(form){
   x.value=""; //清空input里的value
  y.value="";
  u.style.display="none";
  up.style.display="none";
   p.style.display="none";
  } 
 /*btn.onclick=function(form){
  /*if (x!="admin"||y!=123456){
  alert(&#39;账号或密码错误!&#39;);
  }
  //判断账号密码是否为空则弹出
  if (""==x) {
  alert("请输入账号！");
  flag=false;
  return false; 
  }
  else if(""==y){
  alert("请输入密码！");
  flag=false;
  return false;
  }
  if(flag==true){
  flag=true;
  }*/
</script>
</body>
</html>

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