First, be aware it is not possible to totally secure any game. Even commercial software and AAA titles get hacked, and if they can't do it, neither can you (or us). All you can do is make it more difficult to hack.
The best thing you can do is enable 'minify script' on export. That mangles the javascript in to an unreadable mess. You can still edit it, but it's very difficult to figure out which part does what when it's like that.