AJAX is termed as Asynchronous Javascript And XML. Generally, we use following methods in ajax, jquery

• $.post
• $.ajax

In this tutorial, we will learn to pass dynamic key in both ajax method

Checkbox: It is an element in HTML which can be checked or unchecked. It is grouped on the basis of name.

In this tutorial we will learn about validation of checkbox in javascript and retrieve its value in PHP. Checkbox is classified in two types.

• Multiple checkbox
• Single checkbox

1. Multiple checkbox: You can select more than one checkbox, but atleast one checkbox must be selected. In PHP, you have to retrieve its value.

2. Single checkbox: Sometimes you have single checkbox and you have to validate it and retrieve its value in PHP. e.g. You have to agree to terms and condition

It is also expressed as regex. Regular expression is the backbone of form validation. We can validate any form elements using it. Both client side and server side elements can be validated using it. It is used in various programming or scripting language like PHP, JAVASCRIPT, PYTHON, PERL, etc.

It starts with carat(^) and end with dollor($) sign. E.g.

• /^[0-9]/ means starts with digit ie. 0 to 9, but end can be any thing.
• /[0-9]$/ means starting can be any character but it should end with digits.
• /^[0-9]$/ means starting with digit and end with digits.