Javascript validations to validate form in asp.net

Introduction 

Here I will explain how to validate form using JavaScript validations in asp.net 

Description

I have a one sample registration form that contains fields like Username, Password, Confirm Password, First Name, Last Name, Email, PhoneNo and Location.

Now I want to check whether user enter data in all fields or not and I want to check whether user enter correct data in all fields or not by using JavaScript.

If I want to check whether user enters data in textbox or not write script like this 

Calculating the difference between two dates range is 30 days in javascript or validation to Check end date is not greater than start date and two dates range is not more than 30 days using ajax and javascript in asp.net

Introduction:

Here I will explain how to check end date greater than start date and check two dates difference range is 30 days or not using asp.net.

Description:

Previously I explained how to use Ajax Collapsible panel . I explained many articles on Ajax now I will explain to how to set validation to check end date greater than start date or not and check two dates difference range is 30 days using Ajax validator controls. 

how to change the error message of custom validator dynamically using asp.net

Introduction

Here I will explain how to change the error message of custom validator dynamically using asp.net.

Description

I have one textbox, one button and one custom validator to validate the textbox whenever user clicks on button.

In customvalidator I have taken ClientValidationFunction="ClientValidationFunction" this clientside function is used to send error message dynamically by using sender object. This sender object will display ErrorMessage dynamically.