PHP and AJAX - Make a Password Strength Bar that Updates in Real-time

This tutorial will show you how to make a very simple feature which will help your users make more secure passwords, in registration forms. After the user types their password, this script will make a request to a PHP page, which will check the password for lowercase letters, uppercase letters, numbers and symbols. Without reloading the page, a bar displaying the strength of the password will be shown to the user.