
Since the JavaScript runs on the browser, the browser's JavaScript engine must be able to read and interpret it, so there's no way to prevent that.

No, while it's impossible to recover the exact original source code, someone with the time, knowledge and patience can reverse-engineer it. You can show your work to the client knowing that they won't have the source code until the invoice has been paid.

FAQ Why would I want to obfuscate my JavaScript code?
