The verification code automatically validates the PHP backend verification code detection when the form is submitted by Ajax

This article through the source code show how to implement the form submission, the verification code first detect correctness, incorrect then do not submit the form, update the verification code.

1. Front-end Code index.html

 <! DOCTYPE html>
2, back-end verification code detection  checkcode.php
The verification code automatically validates the PHP backend verification code detection when the form is submitted by Ajax