I used the word checksum referring to Jan Goyvaerts's original post. Now, I meant to use that word as a way of expressing "security and/or prevention of hacking" of the javascript code.
There is no way to use that information with the client to make sure that no one messed with the code.
JavaScript is like trusting the valet with your car. You hope that the time when you hand it off to the time you get back into your car that they did not do anything with it. They could have gone through the glove box, trunk, or looked under your hood. You can do preventable stuff, but there is nothing you can do to make sure it is 100% safe other than never using a valet. [aka never serving that JavaScript to the user.]
What are you trying to protect? Maybe there is a better way of "securing" the logic you are trying to hide.
Eric
With a little knowledge, a cast iron skillet is non-stick and lasts a lifetime.