The preference javascript.options.showInConsole controls whether errors or warnings in chrome code are shown in the Error Console.
- Type:boolean
- Default value:  false(truein debug builds)
- Exists by default: yes
- Application support:Firefox 1.0
- Status: Active
- Introduction:2002-02-26
- Bugs: bug 125181 bug 337875
Values
- 
  false
- Only errors and warnings from content code are shown.
- 
  true(default)
- 
  Errors and warnings from both chrome and content are shown in the Error Console.
  Note: Since the Web Console was introduced in Firefox 4 specifically for debugging content, the default value for this preference has changed to trueas of Gecko 2.0.