Constants can be deleted using the delete keyword. const foo = 1; delete foo; typeof foo == 'undefined'
I cannot reproduce this in the latest nightly build. Which version did you test with?
(In reply to comment #1) > I cannot reproduce this in the latest nightly build. Which version did you > test with? > I was using 525.21 (forgot to change version).
*** This bug has been marked as a duplicate of bug 14611 ***