Friday, 2 February 2018

JavaScript Form Validation


Validation is used to validate the form submitted by the user.

JavaScript provides client side validation.

client side validation is  faster than server-side validation.

Through JavaScript, we can validate name, password, email, date, mobile number fields etc.

Example: Registration form  validation
<!doctype html>
<html lang="en:US">
<head>
<title>Create an Account</title>
<meta charset="UTF-8">
</head>

<style>
body{background-image:url("Blank-Background-for-Desktop.jpg")}
#loginbtn{background-color:green;}
#resetbtn{background-color:Red;}
caption{font-size:20px;}
</style>

<script type="text/javascript"> 
function validateform(){
var fname=document.myform.firstname.value;
var lname=document.myform.lastname.value;
var emailID=document.myform.email.value;
var atposition=emailID.indexOf("@"); 
var dotposition=emailID.lastIndexOf("."); 
var password1=document.myform.password.value;
var password2=document.myform.password3.value;

//fname validation(required field validation )
if(fname==null || fname==""){
document.getElementById("mona").innerHTML="  First Name can't be blank"; 
return false;
}
//lname validation(required field validation )

else if(lname==null || lname=="")
 {
  document.getElementById("mona1").innerHTML="  Last Name can't be blank"; 
  return false;
 }



//email validation

else if(atposition<1 || dotposition<atposition+2 || dotposition+2>=emailID.length)
 { 
  document.getElementById("mona2").innerHTML="  Please enter a valid e-mail address"; 
  return false; 
 }

// password validation
else if(password1.length<6)
 {            
  document.getElementById("mona3").innerHTML="  Password must be at least 6 characters long."; 
  return false; 
 }

//confirm password validation

     if(password1==password2){ 
            return true; 
            } 
            else{ 
            document.getElementById("mona4").innerHTML="  password must be same...!!!"; 
            return false; 
 } 


 }
</script>
<body>
<form name="myform" method="post" action="#" onsubmit="return validateform()" > 
<table>
<h1><b>Create an account</b></h1>
<tr>
<td>First Name</td>
<td>: </td>
<td><input type="text" name="firstname"><span id="mona"></span></td>
</tr><br>
<tr>
<td>Last Name</td>
<td>: </td>
<td><input type="text" name="lastname"><span id="mona1"></span></td>
</tr>
<tr>
<td>Email ID</td>
<td>: </td>
<td><input type="text" name="email"><span id="mona2"></span></td>
</tr>
<tr>
<td>Age</td>
<td>: </td>
<td><input type ="number" name="Age"><span id="mona5"></span></td>
</tr><br>
<tr>
<td>Create a new Password</td>
<td>: </td>
<td><input type="password" name="password"><span id="mona3"></span></td>
</tr>
<tr>
<td>Re-enter Password</td>
<td>: </td>
<td><input type="password" name="password3"><span id="mona4"></span></td>
</tr>
<br>
</table>
<button type="submit" name="Submit" id ="loginbtn"><b>Login</b></button>
<button type="button" name="Submit" id="resetbtn"><b>Reset</b></button><br><br></b>
Already Registered!!!&nbsp&nbsp&nbsp&nbsp&nbsp<a href="#">Register Here!!!</a>
</form>
</body>

</html>
Output:


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