All credit cards are 16 digits and the 16th digit can be calculated based on the first 15 numbers.
This means you can use Java Script to check for, and alert the user to, credit card typos.
If any fields are not valid, the form will not be submitted and the user will be informed with error messages for the fields that are causing problems.
To get started, we'll create an HTML page that include a form with the id "contact". It should contain an label, an input (or textarea), and a span that will contain the error message.
Because your database contains sensitive information, hackers may attempt to use your form to submit malicious commands to your backend database.
If you are using a My SQL database, this is called My SQL Injection.
Java Script form validation is a great way to help your users avoid mistakes when filling out a form Alternatively, if you want to protect your server from malicious users, then you should use server side validation because Java Script can be easily bypassed.