What is the best client side scripting language keep in mind that i'm using asp.net and c# ?

Actually ASP.net In Technology,

PHP, ruby, python, perl, are all server side languages, they run on a server,

C# can also use as a Client Side Scripting Language It would be so much nicer than JS.

JAVA SCRIPT : client side scripting means they don't require a server to run, like JavaScript,

it runs directly on a browser, JavaScript is the only language that is supported by all browsers,

other client side languages are not supported like VBScript, coffeeScript, lately Google created a language called Dart, and it's not there yet.

Use Jquery - client side script , it dosn't require server to run , you can validate fields before request the server, the jquery library have alot alot of built in feature will help you alot

C#.NET for Windows Applications

ASP.NET for Web Applications

T-SQL for Databases

ADO.NET for Connecting between SQL Database and C# Application

- Javascript (essentially the client-side scripting language. The rest are variants of it)

- Ajax (Used for implementing JavaScript and XML without affecting the web-page itself)

- Jquery (used as a JavaScript library in which one can easily use commonly used scripts without specifications)

- ActionScript (used to create animated interactive web applications for Adobe Flash Player using Adobe Flash Pro)

Thanks For all , your Response Appreciated !!

Javascript

You can use javascript/Jquery as a client side scriptng languge.  I would suggest using jquery because it has a ot of built in libraries that will help you to minimize your codding efforts. also you can easly communicate with server side scripts using JSON

Jquery - client side script

JavaScript has evolved over the years and have established as a strong client scripting framework. 

We now see lot of open source librarys which are purely based on JavaScript. to mention JQuery I must admit that JQuery has really shown the power of JavaScript. However, JavaScipt is the most misunderstood langauge in the world. I recommend you to look for JavaScript Good Parts by  Douglas Crockford if you do a google on this keywork you will find quite a good sources. 

Hope it helps if so please vote up 

From my point of view Javascript or jquery would be the best client side scripting language due to various factors as cross browser, easy to use,better performance & more.

Use JQuery.

Currently we are using REST services with JSON.