Coding A Brute Forcer

Firstly it generates two numbers. One is the sum of the CharCodes and
the other is the product of multiply each of the charcodes together
and usisng the Modulus function.

If the text string is correct, the string is then used to decode (via
a relatively simple crypt) another string, which then gives you the
correct target url.

I hope that makes sense - if it doesn't, its pretty unimportant as the
question I have is as follows :

In javascript, how do I code something that allows me to cycle through
all the possible text strings. Ideally, I would like to read from a
dictionary file and then start a brute force.

Throughout each cycle, I imagine you just set input_user (in this
case) to the value of the next line in the file. For a dictionary
attack I imagine. That bit isn't too tricky I don't think but I can't
get my head around it. Maybe more coffee would help?

And I'm sure struggling to put together a brute forcer so I turn to
you guys and gals to ask if you could help me and point me in the
right direction on how to code this.

I'm assuming also that the code we end up with, would be generically
useful too as in we could vary the output (going to input_user) in
this instance to another variable and use it with another script?