Show “loading” animation on button click

Question

I want to do something very simple. I have one button in my page.

Answer 1

$("#btnId").click(function(e){
      e.preventDefault();
      $.ajax({
        ...
        beforeSend : function(xhr, opts){
            //show loading gif
        },
        success: function(){

        },
        complete : function() {
           //remove loading gif
        }
    });
});