Browse - Programming Tips - Old - How do I get warnings about undeclared variables in javaScript?

Date: 2009jul26
Language: javaScript

Q.  How do I get warnings about undeclared variables in javaScript?

A.  In Firefox, go to

about:config

And set

javascript.options.strict = true

This is like perl's "use strict;".
It also, helpfully, warns about variables with overlaping scope.
Since this generates lots of warning from things I don't control
(eg jQuery).  I prefer to just turn it on occasionally.