HTML Series

The W3C HTML standard includes support for client-side scripting. It defines how locally executable scripts may be used in a web page. A particular client-side application, such as a web browser, may support several script languages. Script code may be executed as the document loads or at a later time. The World Wide Web Consortium (W3C) is a consortium that produces standards—recommendations, as they call them—for the World Wide Web. ... In computing, HyperText Markup Language (HTML) is the predominant markup language for the creation of web pages. ... Client-side scripting generally refers to the class of computer programs on the web that are executed client-side, by the users web browser, instead of server-side (on the web server). ... Scripting programming languages (commonly called scripting languages or script languages) are computer programming languages designed for scripting the operation of a computer. ... A screenshot of a web page. ... An example of a web browser (Internet Explorer) showing the main Wikipedia web page. ...

Script code can be written directly in the HTML document inside:

• SCRIPT elements
• Intrinsic event attributes
• Script macros

Intrinsic event attributes

Events occur for different elements of a web-page: Event-driven programming is a computer programming paradigm. ...

• Documents (BODY and FRAMESET)
• Forms
• UI elements (Anchor, Control Element, Image)

Script code may be associated with an event and element by writing code in an HTML attribute. The name of the attribute must be that of a supported intrinsic event for the element (for example, "onLoad"). The script is executed whenever the event occurs for that element. These scripts are mostly Javascript. The HTML intrinsic event model consist of the following events: The user interface is the part of a system exposed to users. ...

• Document
  • onLoad
  • onUnload
• Form
  • onSubmit
  • onReset
• Document and UI elements
  • Focus
    • onFocus
    • onBlur
• UI elements
  • Mouse
    • Movement
      • onMouseOver
      • onMouseOut
      • onMouseMove
    • Button
      • onClick
      • onDblClick
      • onMouseDown
      • onMouseUp
  • Keyboard
    • onKeyPress
    • onKeyDown
    • onKeyUp
  • Other (TEXT/TEXTAREA)
    • Lost focus with modified content
      • onChange (also OPTION)
    • Text selection
      • OnSelect

Some browsers support additional event attributes (outside the standard), such as:

• onResize
• onMove
• onScroll
• onAbort

Script macros

Netscape Navigator supported a feature called "JavaScript entities" or "script macros" by which script code could be included in HTML attribute values, using a syntax similar to that of character entity references. For example, the code <img width="&{prompt('Width?')};" src="foo.jpg"> calls the JavaScript prompt() function to ask the user how wide the image should be. Netscape Navigator, also known as Netscape, was a proprietary web browser that was popular during the 1990s. ... HTML has been in use since 1991 (note that the W3C international standard is now XHTML), but the first standardized version with a reasonably complete treatment of international characters was version 4. ...

The HTML 4.01 specification reserves a syntax for the "future support of script macros" in HTML attributes, but they have not been incorporated into later standards and are not supported by any current browser.