Javascript Event Object

Properties

Different types of events have different properties, which you’ll learn
about later in the chapter. Here are a few properties common to all standard
Event objects:
■ type The type of the event, like “click,” “load,” or “keypress.”
■ target The element that originally dispatched the event. This may not
be the same as the element to which the event handler is attached.
■ currentTarget The element to which you attached the event handler.
In most cases, it is synonymous with the this keyword. If you change
the context of the event handler with call() or apply(), you can still
access the element with currentTarget.
■ eventPhase A number that indicates whether the event is currently
capturing (1), bubbling (3), or at the target element (2). Find out more
information in the “Event Bubbling and Capturing” section later in this
chapter.
■ timeStamp A number in seconds that represents the time at which the
event occurred.

<a id="link" href="http://www.google.com">Don't go to
Google</a>
var link = document.getElementById("link");
link.addEventListener("click", dontFollowLink, false);
function dontFollowLink(event) {
alert("Not going to " + this.href);
event.preventDefault();
}

In Internet Explorer, the Event object isn’t available as an argument
of the handler. Instead, it’s a property of window. To write crossbrowser
DOM Level 0 code, look for the Event object in both places.
function handler(event) {
event = event || window.event;
}