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The value of the event handler is one or a series of JavaScript expressions, methods, and function calls separated by semicolons, and enclosed in quotes. When an event occurs, the browser will execute this code.
HTML 4 One of the new features is that it can enable HTML events to trigger behaviors in the browser, such as starting a JavaScript script when a user clicks on an HTML element.
The following table provides standard event attributes that can be inserted into HTML/In XHTML elements, to define event behavior.
HTML5 : HTML5New event attributes.
The event is triggered by the window (for the <body> tag):
| Attribute | Value | Description |
| onafterprintHTML5 | script | Run the script after the document is printed |
| onbeforeprintHTML5 | script | Run the script before the document is printed |
| onbeforeonloadHTML5 | script | Run the script before the document is loaded |
| onblur | script | Run the script when the window loses focus |
| onerrorHTML5 | script | Run the script when an error occurs |
| onfocus | script | Run the script when the window receives focus |
| onhaschangeHTML5 | script | Run the script when the document changes |
| onload | script | Run the script when the document is loaded |
| onmessageHTML5 | script | Run the script when a message is triggered |
| onofflineHTML5 | script | Run the script when the document goes offline |
| ononlineHTML5 | script | Run the script when the document goes online |
| onpagehideHTML5 | script | Run the script when the window is hidden |
| onpageshowHTML5 | script | Run the script when the window is visible |
| onpopstateHTML5 | script | Run the script when the window history changes |
| onredoHTML5 | script | Run the script when the document performs a redo operation |
| onresizeHTML5 | script | Run the script when the window size is adjusted |
| onstorageHTML5 | script | Run the script when the Web Storage area is updated (when data in the storage space changes) |
| onundoHTML5 | script | Run the script when the document performs an undo operation |
| onunloadHTML5 | script | Run the script when the user leaves the document |
Form events are triggered in HTML forms (applicable to all HTML elements, but the HTML element must be within the form):
| Attribute | Value | Description |
| onblur | script | Run the script when an element loses focus |
| onchange | script | Run the script when an element changes |
| oncontextmenuHTML5 | script | Run the script when the context menu is triggered |
| onfocus | script | Run the script when an element receives focus |
| onformchangeHTML5 | script | Run the script when the form changes |
| onforminputHTML5 | script | Run the script when the form receives user input |
| oninputHTML5 | script | Run the script when an element receives user input |
| oninvalidHTML5 | script | Run the script when an element is invalid |
| onreset | script | Run the script when the form is reset. HTML 5 Not supported. |
| onselect | script | Run the script when an element is selected |
| onsubmit | script | Run the script when the form is submitted |
| Attribute | Value | Description |
| onkeydown | script | Run the script when the key is pressed |
| onkeypress | script | Run the script when the key is pressed and released |
| onkeyup | script | Run the script when the key is released |
Triggered by mouse events, similar to user actions:
| Attribute | Value | Description |
| onclick | script | When clicking the mouse, run the script |
| ondblclick | script | When double-clicking the mouse, run the script |
| onmousedown | script | The script runs when the mouse button is pressed |
| onmousemove | script | The script runs when the mouse pointer moves |
| onmouseout | script | The script runs when the mouse pointer moves out of the element |
| onmouseover | script | The script runs when the mouse pointer is moved over the element |
| onmouseup | script | The script runs when the mouse button is released |
| onmousewheelHTML5 | script | The script runs when the mouse wheel is scrolled |
Triggered by dragging the mouse, similar to user behavior:
| Attribute | Value | Description |
| ondragHTML5 | script | The script runs when a draggable element is being dragged |
| ondragendHTML5 | script | The script runs when the drag operation ends |
| ondragenterHTML5 | script | The script runs when the element is dropped onto a valid drag-and-drop target |
| ondragleaveHTML5 | script | The script runs when the element leaves a valid drag-and-drop target |
| ondragoverHTML5 | script | The script runs when the element is dragged over a valid drag-and-drop target |
| ondragstartHTML5 | script | The script runs when the drag operation starts |
| ondropHTML5 | script | The script runs when a draggable element is being dragged and dropped |
| onscrollHTML5 | script | The script runs when the scrollbar of a scrolling element is scrolled |
Triggered by video (videos), images (images), or audio (audio), commonly used in HTML media elements like <audio>, <embed>, <img>, <object>, and <video>):
| Attribute | Value | Description |
| onabort | script | The script runs when an abort event occurs |
| oncanplayHTML5 | script | The script runs when the media can start playing but may need to stop due to buffering |
| oncanplaythroughHTML5 | script | The script runs when the media can be played to the end without stopping due to buffering |
| ondurationchangeHTML5 | script | The script runs when the media length changes |
| onemptiedHTML5 | script | The script runs when the media resource element becomes unexpectedly empty (due to network errors, loading errors, etc.) |
| onendedHTML5 | script | The script runs when the media has reached the end |
| onerrorHTML5 | script | The script runs when an error occurs during the loading of the element |
| onloadeddataHTML5 | script | The script runs when loading media data |
| onloadedmetadataHTML5 | script | The script runs when the duration of the media element and other media data has been loaded |
| onloadstartHTML5 | script | The script runs when the browser starts loading media data |
| onpauseHTML5 | script | The script runs when the media data is paused |
| onplayHTML5 | script | The script runs when the media data is about to start playing |
| onplayingHTML5 | script | The script runs when the media data has started playing |
| onprogressHTML5 | script | The script runs while the browser is fetching media data |
| onratechangeHTML5 | script | Script runs when the playback rate of the media data changes |
| onreadystatechangeHTML5 | script | Script runs when the ready state (ready-state) changes |
| onseekedHTML5 | script | Script runs when the media element's positioning attribute [1No longer true and positioning has ended |
| onseekingHTML5 | script | Script runs when the media element's positioning attribute is true and positioning has started |
| onstalledHTML5 | script | Script runs when there is an error in the process of fetching media data (delayed) |
| onsuspendHTML5 | script | Script runs when the browser is already fetching media data but has stopped before retrieving the entire media file |
| ontimeupdateHTML5 | script | Script runs when the media changes its playback position |
| onvolumechangeHTML5 | script | Script runs when the volume of the media changes or when the volume is set to mute |
| onwaitingHTML5 | script | Script runs when the media has stopped playing but intends to continue playing |
| Attribute | Value | Description |
| onshowHTML5 | script | Triggered when the <menu> element is displayed in context |
| ontoggleHTML5 | script | Triggered when the user opens or closes the <details> element |