Converts javascript command into no alnum version using only []()+! characters (unless you input extras).

Intended input: one line, no whitespace, no variables, function definitions or conditionals.

There are some nuances, for instance "falseundefined" must be "false"+""+"undefined". Let me know if you find improvements. Page tested with Firefox only.

Example:
alert(document.getElementById("txt").value+String.fromCharCode(33))