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 a web browser, may support several script languages. Script code may be executed as the document loads or at a later event.

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

• SCRIPT elements
• Intrinsic event attributes
• Script macros

The SCRIPT element

The SCRIPT element may occur zero or more times within the HEAD and BODY tag. Scripts within script elements are processed as the document loads.

Intrinsic event attributes

Events occur for different elements of a web-page:

• 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.

The HTML intrinsic event model consist of the following events:

• 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

Script code may be included as an HTML attribute value. The code must be preceded by an ampersand. NOTE: Script macros are often left out of implementations.