Mousedown event not triggered immediately

I bind a mousedown event to a button. It is not triggered immediately when I press the button, but it will be triggered after a complete “click”, which means it will trigger together with “mouseup” event. Can anybody help me to solve the problem?

I ran across the same problem. In my case it was caused by the fact that I tested my app in Firefox Responsive Design Mode with touch simulation enabled. When I disabled touch simulation all mouse events worked as expected.