• Intro
• Firefox Console
• Firefox Debugger

• Debug

  you should view these 2 videos BEFORE producing javascript code
  Note : You can ONLY use the Debugger to debug Javascript code - NOT HTML
  Thus, you can only set breakpoints within the Javascript code ONLY ( e.g. within functions).
  Firefox can be used to :
  Identify Syntax Errors - use Web Console
  Debug Code - use the Debugger
  Both of these techniques are explained the videos below
  NOTE that the W3C validator used in the 'Web Console' video is an OLDER version - it used to give “1 warning” for HTML5 validation