How to call the function on click event?

Rather than giving you a quick example, I would recommend you to head to the official documentation instead to get a grasp on how event binding works in knockout.js:

 

http://knockoutjs.com/documentation/click-binding.html 

You can use OnClientClick attribute for your asp button as:

 

 

To give you proper knowledge I would like to share a link. In which Microsoft has explained each and every step.

 

https://docs.microsoft.com/en-us/dotnet/api/system.web.ui.webcontrols.button.onclientclick?redirectedfrom=MSDN&view=netframework-4.7.2#System_Web_UI_WebControls_Button_OnClientClick

 

It will definitely help and answer your question.

Hello

 

Check this

 

You can try something like

 

 

http://jsfiddle.net/bryiantan/uajyh24w/