When a radio button is selected addition check attribute is not added to it. You have to enter "checked".

BY Best Interview Question ON 29 Jun 2019

Example

$(document).ready(function(){
    $("input[type='button']").on('click', function(){
       var radioValue = $("input[name='gender']:checked").val();
       if(radioValue){
          alert(radioValue);
       }
    });
});