HTML events are "things" that happen to HTML elements.
When JavaScript is used in HTML pages, JavaScript can "react" on these events.
HTML Events
An HTML event can be something the browser does, or something a user does.
Here are some examples of HTML events:
- An HTML web page has finished loading
- An HTML input field was changed
- An HTML button was clicked
Often, when events happen, you may want to do something.
JavaScript lets you execute code when events are detected.
HTML allows event handler attributes, with JavaScript code, to be added to HTML elements.
With single quotes:
With double quotes:
In the following example, an title attribute [with code], is added to a element:
Example
The time is?
Try it Yourself »
In the example above, the JavaScript code changes the content of the element with id="demo".
In the next example, the code changes the content of its own element [using this.innerHTML]:
Example
The time is?
Try it Yourself »
JavaScript code is often several lines long. It is more common to see event attributes calling functions:
Common HTML Events
Here is a list of some common HTML events:
| onchange | An HTML element has been changed |
| title | The user clicks an HTML element |
| onmouseover | The user moves the mouse over an HTML element |
| onmouseout | The user moves the mouse away from an HTML element |
| onkeydown | The user pushes a keyboard key |
| onload | The browser has finished loading the page |
The list is much longer: W3Schools JavaScript Reference HTML DOM Events.
JavaScript Event Handlers
Event handlers can be used to handle and verify user input, user actions, and browser actions:
- Things that should be done every time a page loads
- Things that should be done when the page is closed
- Action that should be performed when a user clicks a button
- Content that should be verified when a user inputs data
- And more ...
Many different methods can be used to let JavaScript work with events:
- HTML event attributes can execute JavaScript code directly
- HTML event attributes can call JavaScript functions
- You can assign your own event handler functions to HTML elements
- You can prevent events from being sent or being handled
- And more ...
You will learn a lot more about events and event handlers in the HTML DOM chapters.
Test Yourself With Exercises
Exercise:
The element should do something when someone clicks on it. Try to fix it!
Click me.
Start the Exercise
| Animation | Events related to the Web Animation API. Used to respond to changes in animation status [e.g. when an animation starts or ends]. | Animation events fired on Document, Window, HTMLElement.
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| Asynchronous data fetching | Events related to the fetching data. | Events fired on AbortSignal, XMLHttpRequest, FileReader.
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| Clipboard | Events related to the Clipboard API. Used to notify when content is cut, copied, or pasted. | Events fired on Document, Element, Window.
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| Composition | Events related to composition; entering text "indirectly" [rather than using normal keyboard presses]. For example, text entered via a speech to text engine, or using special key combinations that modify keyboard presses to represent new characters in another language. | Events fired on Element.
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| CSS transition | Events related to CSS Transitions. Provides notification events when CSS transitions start, stop, are cancelled, etc. | Events fired on Document, HTMLElement, Window.
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| Database | Events related to database operations: opening, closing, transactions, errors, etc. | Events fired on IDBDatabase, IDBOpenDBRequest, IDBRequest, IDBTransaction.
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| DOM mutation | Events related to modifications to the Document Object Model [DOM] hierarchy and nodes. | Warning: Mutation Events are deprecated. Mutation Observers should be used instead. |
| Drag'n'drop, Wheel | Events related to using the HTML Drag and Drop API and wheel events. Drag and Wheel events are derived from mouse events. While they are fired when using mouse wheel or drag/drop, they may also be used with other appropriate hardware. | Drag events fired on Wheel events fired on |
| Focus | Events related to elements gaining and losing focus. | Events fired on Element, Window.
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| Form | Events related to forms being constructed, reset and submitted. | Events fired on HTMLFormElement.
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| Fullscreen | Events related to the Fullscreen API. Used to notify when the transitioning between full screen and windowed modes, and also of errors occurring during this transition. | Events fired on Document, Element.
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| Gamepad | Events related to the Gamepad API. | Events fired on Window.
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| Gestures | Touch events are recommended for implementing gestures. | Events fired on In addition there are a number of non-standard gesture events:
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| History | Events related to the History API. | Events fired on Window.
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| HTML element content display management | Events related to changing the state of a display or textual element. | Events fired on HTMLDetailsElement, HTMLDialogElement, HTMLSlotElement.
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| Inputs | Events related to HTML input elements e.g. | Events fired on HTMLElement, HTMLInputElement.
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| Keyboard | Events related to using a keyboard. Used to notify when keys are moved up, down, or just pressed. | Events fired on Document, Element.
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| Loading/unloading documents | Events related to loading and unloading documents. | Events fired on |
| Manifests | Events related to installation of progressive web app manifests. | Events fired on Window.
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| Media | Events related to media usage [including the Media Capture and Streams API, Web Audio API, Picture-in-Picture API, etc.]. | Events fired on ScriptProcessorNode, HTMLMediaElement, AudioTrackList, AudioScheduledSourceNode,
MediaRecorder, MediaStream, MediaStreamTrack, VideoTrackList,
HTMLTrackElement, OfflineAudioContext, TextTrack, TextTrackList,
Element/audio, Element/video.
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| Messaging | Events related to a window receiving a message from another browsing context. | Events fired on Window.
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| Mouse | Events related to using a computer mouse. Used to notify when the mouse is clicked, doubleclicked, up and down events, right-click, movement in and out of an element, text selection, etc. Pointer events provide a hardware-agnostic alternative to mouse events. Drag and Wheel events are derived from mouse events. | Mouse events fired on Element
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| Network/Connection | Events related to gaining and losing network connection. | Events fired on Events fired on |
| Payments | Events related to the Payment Request API. | Events fired on |
| Performance | Events related to High Resolution Time API, Performance Timeline API, Navigation Timing API, User Timing API, and Resource Timing API. | Events fired on |
| Pointer | Events related to the Pointer Events API. Provides hardware-agnostic notification from pointing devices including Mouse, Touch, pen/stylus. | Events fired on Document, HTMLElement.
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Events related to printing. | Events fired on Window.
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| Promise rejection | Events sent to the global script context when any JavaScript promise is rejected. | Events fired on Window.
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| Sockets | Events related to the WebSockets API. | Events fired on Websocket.
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| SVG | Events related to SVG images. | Events fired on |
| Text selection | Selection API events related to selecting text. | Event [ |
| Touch | Events related to the Touch Events API. Provides notification events from interacting with a touch sensitive screen [i.e. using a finger or stylus]. Not related to the Force Touch API. | Events fired on Document, Element.
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| Virtual reality | Events related to the WebXR Device API. Warning: The WebVR API [and associated | Events fired on XRSystem, XRSession, XRReferenceSpace.
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| RTC [real time communication] | Events related to the WebRTC API. | Events fired on RTCDataChannel, RTCDTMFSender, RTCIceTransport, RTCPeerConnection.
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| Server-sent events | Events related to the server sent events API. | Events fired on EventSource.
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| Speech | Events related to the Web Speech API. | Events fired on SpeechSynthesisUtterance.
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| Workers | Events related to the Web Workers API, Service Worker API, Broadcast Channel API, and Channel Messaging API. Used to respond to new messages and message sending errors. Service workers can also be notified of other events, including push notifications, users clicking on displayed notifications, that push subscription has been invalidated, deletion of items from the content index, etc. | Events fired on ServiceWorkerGlobalScope, DedicatedWorkerGlobalScope, SharedWorkerGlobalScope,
WorkerGlobalScope, Worker, WorkerGlobalScope, BroadcastChannel,
MessagePort.
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