What could be easier than setting up an HTML form that captures email addresses, say for a newsletter or notifications?
Mistyping an email address in that form, of course, and then have your browser remember that incorrect address for all the signup forms to come.
This is also a good idea to validate the form before submitting the data to the server side used to verify that the input given value is a possible valid email address.
This function makes sure the email address has one "@", atleast one ".".
For example, if you are going to send an email confirmation letter, the email address should be included in the form fields, and it should be an email address that works.
In your example, the action is "" and I don't see in your validation script where you actually submit the form.
Often, email validation code for web applications checks only for the position of @ and period characters, also assuming the @ character will be in the front of period. Did you know you can use a Java Script Regular Expressions method to check email addresses?