Possible to enable "strict mode" in FireBug and Chrome's console?

The firebug console works by wrapping all the code in an "eval" call so the first statement in your script is no longer "use strict" - hence it is disabled. You could try wrapping your code in a function to enforce "use strict" for that particular function but the best solution I know of is to skip the console and test straight in the page itself.

use shift+enter to input 'use strict'

like this