Can I make Firefox do strict (like perl's use strict) checking?

Programming Tips - Old - Can I make Firefox do strict (like perl's use strict) checking?

Date: 2009nov9 Language: javaScript Q. Can I make Firefox do strict (like perl's use strict) checking? A. Yes, in about:config set:

javascript.options.strict = true

I'd prefer a way to turn this off/on in code but that doesn't currently exist.