3 ms·

No you can't. You can do something like function(undefined) {}, but the global 'undefined' is non-writable and non-configurable.

• ahoge 12y ago
  That's an ES5 change. With ES3, you can overwrite NaN, Infinity, and undefined.
  • LunaSea 12y ago
    Only in strict mode I though no ?
    • ahoge 12y ago
      Generally. Technically, it's a "breaking change". As you can imagine, this didn't actually affect anyone.