3.3 Use JavaScript wisely

Recommendations

• Important content or functionality should not rely on JavaScript alone:
  • Ensure the content still makes sense and can still be used when scripts are turned off:
    • Provide alternative content using the <noscript> tag
  • JavaScript enabled content that requires use of the mouse must be accessible without the mouse:
    • Use redundant event handlers:
      • OnKeypress + OnClick
      • OnMousedown + OnKeydown
      • OnMouseUP + OnKeyup
      • Do not use OnDblclick
• Use redundant server side scripts as well as client side scripts for form validation, etc.
• Avoid use of JavaScript links:
  • Unless you provide an alternative via <noscript>
• Avoid automatic submission of forms, etc.

Tip: Simple image rollover effects, etc. are fine as long as the image replacement doesn't contain additional information.

Examples

Device independent event handlers OnFocus, OnBlur, OnSelect would be the preferred way to detect events, unfortunately current browser support is patchy at best.

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