This means that the input data must contain at least an @ sign and a dot (.).Also, the @ must not be the first character of the email address, and the last dot must at least be one character after the @ sign.Form data that typically are checked by a Java Script could be: validate Form On Submit ( ) This is a main function that calls a series of subfunctions, each of which checks a single form element for compliance.If the element complies than sufunction returns an empty string.For that we use the seacrh() method and two more regular expressions: /(a-z) / and /(0-9)/.
If its not blank, the function returns an empty string.
At first we check if the user entered anything at all in the email field.
Next, we use regular expression and the test() method to check the field for a compliance.
For the majority of your users, Java Script form validation will save a lot of time up front, but double-checking the data on the server remains necessary, in case the user has turned Java Script off.