Form validity checking with js

Form checking is very important script for getting valid content. The js is the best way to check validity.
Here from name is "sign_up_form". Input value getting process is document.forms["<form_name>"]["<input_fields_name>"].value;.
Code:

<script type="text/javascript">
function validateForm()
{
 //  validateForm function starts here
 // Validate the fill in of First Name
 var x=document.forms["sign_up_form"]["First_Name"].value;
  
 if (x==null || x=="")
 {
  alert("First name must be filled out");
  return false;
 }
 // Validate the fill in of Last Name
 var x=document.forms["sign_up_form"]["Last_Name"].value;
  
 if (x==null || x=="")
 {
  alert("Last name must be filled out");
  return false;
 }

 // code for email validation starts here
 var x=document.forms["sign_up_form"]["Email"].value;
 var atpos=x.indexOf("@");
 var dotpos=x.lastIndexOf(".");
 if (atpos<1 || dotpos<atpos+2 || dotpos+2>=x.length)
 {
  alert("Not a valid e-mail address");
  return false;
 }
 //code for email validation ends here

 //code for password match starts here
 var x=document.forms["sign_up_form"]["pwd"].value;
 var y=document.forms["sign_up_form"]["re_pwd"].value;
 var z=x.length;
 if((x!=y || !x))
 {
  alert("Password does not match!!! Please give correct password");
  return false;
 }
 //code for password match ends here
 
}//  validateForm function ends here 

</script>

Form validity checking with js

Saturday, February 23, 2013