how to create custom events in global javascript with optimizely

customEventsOptimizely.js

$(document).ready( function() {
    $("selector").click( function(e) {
      e.preventDefault();
      window['optimizely'] = window['optimizely'] || [];
      window.optimizely.push(["trackEvent", "custom_event_id"]);
      alert("Hello there");
    });
});