Without any ability to opcache or byte code it and encrypt it. It's not going to take much to crack it. You think bytecode is difficult to crack? :-) One thin

Without any ability to opcache or byte code it and encrypt it. It's not going to take much to crack it. You think bytecode is difficult to crack? :-) One thing you can do is compile your JavaScript code to asm.js. That is low level enough to make things pretty difficult to reverse. Until Hex-Rays Decompiler for asm.js comes out of course :-)