在javascript游戏中是否可以完全禁止用户篡改JavaScript？

I'm starting to put together an online game in which the majority of the game is written in javascript. It occurred to me from a security perspective that with tools like FireBug that the player of the game could easily manipulate the javascript and do things that the game did not intend (e.g. enable the character to jump twice as high).I'm starting to put together an online game in