This is for Scala scale files (.scl). Scala is a software program used for experimenting with musical tunings. This has nothing to do with the programming language also called Scala.
This was heavily inspired by the Lua script that eventually became a Renoise plugin:
http://forum.renoise.com/index.php/topic/28495-snippet-load-scala-scl-tuning-file
You point it to an .scl file, and it returns an array of frequencies, where the index matches the MIDI note (0 -127).
Example:
var scl = require('scl-to-frequencies');
scl('/path/to/scl/file');
// Defaults to Middle C at MIDI note 48 and 261.625565300598623 Hz.
scl('/path/to/scl/file', 48, 261.625565300598623);