Types of Events

In the early days of the Web, client-side programmers made do with only a small set of events: “load”, “click”, “mouseover”, and the like. These legacy event types are well supported by all browsers and are the subject of Legacy Event Types. As the web platform has grown to include more powerful APIs, the set of events has grown large. No single standard defines a complete set of events, and at the time of this writing, the number of events supported by browsers is growing rapidly. These new events come from three sources:

  • The DOM Level 3 Events specification, which after a long period of inactivity is being actively worked on under the auspices of the W3C. DOM events are covered in DOM Events.

  • Many new APIs in the HTML5 specification (and related spin-off specifications) define new events for things like history management, drag-and-drop, cross-document messaging, and audio and video playback. HTML5 Events gives an overview of these events.

  • The advent of touch-based and JavaScript-enabled mobile devices, such as the iPhone, have required the definition of new touch and gesture event types. See Touchscreen and Mobile Events for some Apple-specific examples.

Note that many of these new event types are not yet widely implemented and are defined by standards that are still in draft stage. The subsections that follow provide an overview of the events, but do not document each one in detail. The rest of this chapter covers the event handling model comprehensively and includes ...

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