Here I am giving you the form validation codes in Java Script. These are simple meta characters which do pattern matching. If the entered characters in the field is not in lower case or upper case. When it’s about checking contact field or zip code field, one need to check whether only the number have been entered or not.
Regular expression helps you in pattern matching in string. : Matches any single charcter except a new line : Matches the preceding character or repeated character. The basic expression for matching entered value as number in the field is: /^[0-9] $/.
If an user miss out any field, than the form will display error message.
Checking for form completion: The first step of form validation is to check, whether the user have entered information in all the fields or not.
This not only creates a standardized string that can be later used in a comparison or stored in a database, but also ensures that the data that is received on the server end contains only the expected data.
[a-z] : It matches characters from lowercase ‘a’ to lowercase ‘z’. If by mistake, user skips entering any detail, soon the alert message appear on the form.
The problem with the server side validation is that the people that make an honest mistake must suffer a page refresh.
As an answer to this problem most sites will use both forms of validation.
This is a great way to validate the input since the user will be notified before submitting the data if it is valid or not.
The problem with validating user input on the client side is that there is no security.