Explanation/Reference:
jQuery provides a way to trigger the event handlers bound to an element without any user interaction via the .trigger() method.
jQuery's event handling system is a layer on top of native browser events. When an event handler is added using .on( "click", function() {...} ), it can be triggered using jQuery's .trigger( "click" ) because jQuery stores a reference to that handler when it is originally added. Additionally, it will trigger the JavaScript inside the onclick attribute.
Reference: Triggering Event Handlers