Information About What Happened

When an event fires, the browser automatically creates an event object and passes it as the first argument to your handler function. This object contains all the details about what just occurred.

elem.addEventListener('click', function(event) {
  console.log(event.type);        // "click" — the type of event
  console.log(event.currentTarget); // the element the handler is attached to
  console.log(event.clientX + ':' + event.clientY); // cursor coordinates in the window
});

Key Properties

Property	Description
event.type	The event name (e.g., "click", "keydown")
event.target	The deepest element that was actually clicked
event.currentTarget	The element the handler is bound to (same as this inside the handler)
event.clientX / clientY	Mouse cursor coordinates relative to the browser window
event.timeStamp	When the event occurred (milliseconds since page load)