gistfile1.js

function readAllHelps (cb) {
  var help_text = []
    , didError = false
  function error (er) {
    if (didError) return undefined
    didError = true
    cb(er)
  }
  fs.readdir('help', function(er, files) {
    if (err) return error(er)
    var len = files.length
    files.forEach(function (file) {
      fs.readFile('help/'+file, function(er, data) {
        if (didError) return undefined
        if(er) return error(er)
        help_text[file] = data
        if (0 === --len) cb(null, help_text)
      })
    })
  })
}

Try something like this: http://gist.github.com/429797

Note how readAllHelps is abstracted into its own function, so you pass your callback in there, and get notified when all the help files have been read.

Thanks so much, you're a great help !

I think I now get how to structure my code thanks to your example.

I would never have come up with the counter decrementation to know when to call the callback... Very clever, I'll remember that trick.