PHP + Ajax check whether the user name or email has been registered with an instance. tutorial _ php skills

This article mainly introduces PHP + Ajax to check whether an instance exists during user name or email registration. it is a very common and important function. it is often used in forum registration or member registration, if you need it, you can refer to PHP + Ajax to check whether a user name or email already exists during registration. it is a common important function in the forum or membership system. This article describes how to implement this function in the form of an instance. The procedure is as follows:

I. PHP detection page

The check. php page code is as follows: