Firstly you have a syntax error
$(function(){
$("body").on("test", function(){
alert("test triggered");
}); < ---- Missing this
$("body").trigger("test");
});
Secondly you cannot trigger the event from the console , as $(function() {});
forms a closure and you will not have access to any of the methods inside them
For it to work like you are expecting , put a debug point in your script file and then try to trigger the event. It works now as the events are in scope.