Can i break up a js into multiple files?

Yes, but you might not want to.

There are 2 ways to do this that I'm aware of:

1. Put your code (or some of it) in your jsextensions folder.

2. Use File + eval:

/* seriously, don't use this unless you really know what's in the file. */
jsInclude.local = 1;
function jsInclude(filename) {
    var f = new File(filename);
    eval(readWholeFile(f));
}

readWholeFile.local = 1;
function readWholeFile(f) {
    var BLOCK_SIZE = 1024;
    if(f.isopen) {
    var s = "";
    var l;
    while(l = f.readstring(1024)) {
        s += l;
    }
    return s;
    }
}