node.js - Pass additional parameter to Javascript callback function

I need to watch a small number of directories in a Node.JS application:

function updated(event, filename){
    log("CHANGED\t/share/channels/" + filename);
}
for(i in channels)
    fs.watch('share/channels/' + channels[i], {persistent: false}, updated);

The problem is that fs.watch only passes the filename to the callback function, without including the directory it's in. Is there a way I can somehow pass in an extra parameter to the updated() function so it knows where the file is?

I think I'm looking for something similar to Python's functools.partial, if that helps any.

Answer

You can use Function.bind:

function updated(extraInformation, event, filename) {
    log("CHANGED\t/share/channels/" + extraInformation + filename);
}

for(i in channels)

    fs.watch('share/channels/' + channels[i], {persistent: false},
              updated.bind(null, 'wherever/it/is/'));