What is form validation?
- Form validation is the process of checking the forms that have been filled in correctly before they are processed.
- It provides a method to check the user entered information on client-side before the data is submitted to the server-side. It includes two methods for validating forms:
- It displays alerts for incorrect data entered by the user.
- Client-side validation is faster than Server-side validation.
1. Server-Side (ASP, PHP)
2. Client-Side (JavaScript)
Example : Simple Form Validation Program
validation.html //File name
<html>
<body>
<script>
function validateemail()
{
var a = document.myform.email.value;
var atposition = a.indexOf("@");
var dotposition = a.lastIndexOf(".");
if (atposition<1 || dotposition<atposition+2 || dotposition+2>=a.length)
{
alert("Please Enter a valid E-mail Id");
return false;
}
}
</script>
</body>
<body>
<form name="myform" method="post" action="validpage.html" onsubmit="return validateemail();">
Enter Your Email Id: <input type="text" name="email"><br/>
<input type="submit" value="Submit">
</form>
</body>
</html>
validpage.html //File name
<html>
<body>
<script type="text/javascript">
alert("You are a Valid User !!!");
</script>
</body>
</html>
Output:
