JavaScript form validation example to verify whether the form item is empty

JavaScript form validation example to verify whether the form item is empty_javascript skills

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Release： 2016-05-16 15:20:37

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Form verification is essential for almost every website that requires registration or login. Some verifications are very complicated and can be said to be various requirements for you. However, this chapter only introduces the simplest form. The verification method is to determine whether it is empty. Some websites with lower requirements have already met this need.

The code is as follows:

<!DOCTYPE html> 
<html> 
<head> 
<meta charset=" utf-8"> 
<meta name="author" content="http://www.jb51.net/" /> 
<title>js简单表单验证</title> 
<script type="text/javascript">
window.onload=function()
{
var bt=document.getElementById("bt");
bt.onclick=function()
{
if(document.myform.name.value=="")
{
alert("用户名不能为空!");
document.myform.name.focus();
return false;
} 
else if(document.myform.pw.value=="")
{
alert("密码不能为空!");
document.myform.pw.focus();
return false; 
}
}
}
</script>
</head>
<body>
<form action="index.php" method="get" name="myform">
<ul>
<li>姓名:<input type="text" name="name" id="name" /></li>
<li>密码:<input type="text" name="pw" id="age" /></li>
<li><input type="submit" id="bt"/></li>
</ul> 
</form>
</body>
</html>

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The above code can perform simple form verification when the submit button is clicked. If the form item is empty, a prompt will pop up and the focus will be placed on the current form item. The code is relatively simple and will not be introduced here. , you can refer to related readings.

Let’s take a look at the js verification form example code:

gspan.html

 <html>
 <head>
 <title>表单验证实例</title>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-" />
 <script src="check.js" type="text/javascript"></script>
 <style>
 span{ font-size:px; }
 .stats{ color : #ccc; }
 .stats{ color :black; }
 .stats{ color :red; }
 .stats{ color :green; }
 </style>
 </head>
 <body>
 <form method="post" action="reg.php" onsubmit="return regs('click')" >
 用户名：<input type="text" name="username" /><span class="stats">用户名不能为空</span><br/>
 邮箱：<input type="text" name="email" /><span class="stats">邮箱不能为空</span><br/>
 密码：<input type="password" name="password" /><span class="stats">密码不能为空</span><br/> 
 确认密码：<input type="password" name="chkpass" /><span class="stats">密码不能为空</span><br/>
 <input type="submit" />
 </form>
 </body>
 </html>

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check.js

function gspan(cobj){ //获取表单后的span 标签 显示提示信息
if (cobj.nextSibling.nodeName != 'SPAN'){ 
gspan(cobj.nextSibling); 
} else { 
return cobj.nextSibling;
}
} 
//检查表单 obj【表单对象】， info【提示信息】 fun【处理函数】 click 【是否需要单击， 提交时候需要触发】 
function check(obj, info, fun, click){ 
var sp = gspan(obj); 
obj.onfocus = function(){ 
sp.innerHTML = info; 
sp.className = 'stats';
}
obj.onblur = function(){
if (fun(this.value)){
sp.innerHTML = "输入正确！";
sp.className = "stats";
} else {
sp.innerHTML = info;
sp.className = "stats";
}
}
if (click == 'click'){
obj.onblur();
}
}
onload = regs; //页面载入完执行
function regs(click){
var stat = true; //返回状态， 提交数据时用到
username = document.getElementsByName('username')[];
password = document.getElementsByName('password')[];
chkpass = document.getElementsByName('chkpass')[];
email = document.getElementsByName('email')[];
check(username, "用户名的长度在-之间", function(val){
if (val.match(/^\S+$/) && val.length >= && val.length <=){
return true;
} else {
stat = false;
return false;
}
}, click);
check(password, "密码必须在-位之间", function(val){
if (val.match(/^\S+$/) && val.length >= && val.length <=){
return true;
} else {
stat = false;
return false;
}
}, click);
check(chkpass, "确定密码要和上面一致，规则也要相同", function(val){
if (val.match(/^\S+$/) && val.length >= && val.length <= && val == password.value){
return true;
} else {
stat = false;
return false;
}
}, click);
check(email, "请按邮箱规则输入", function(val){
if (val.match(/\w+@\w+\.\w/)){
return true;
} else {
stat = false;
return false;
}
}, click);
return stat;
}

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