how to track confirm cancel event of alert in code behind in C#

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C#

ASP.NET

Javascript

AlertDialog

My requirement is very simple yet very seems to be complicated !!

I am using C# code and java-script.

I want to use an alert message with confirm / cancel button and i want to track the user click from code behind say if he has pressed confirm button of alert message or say if he has clicked on cancel button of alert message.

say from c# code behind page i have called confirmDuplicateCustomerCreation

function confirmDuplicateCustomerCreation() {
confirm('Customer with same details already exists. Do you want to continue?')
}
then is there any way to track whether the user has clicked on confirm or cancel.... ??