booh!

to-args.js

var assert = require('assert')
  , result;

function toArgs(val){
  if (Array.isArray(val[0])) return val[0];
  var len = val.length;
  var ret = new Array(len);
  for (var i = 0; i < len; ++i) {
    ret[i] = val[i];
  }
  return ret;
}

// varargs

result = (function(){
  return toArgs(arguments);
})('a', 'b', 'c');

assert(result instanceof Array);
assert(result.length == 3);

// arrays
result = (function(){
  return toArgs(arguments);
})(['a', 'b', 'c']);

assert(result instanceof Array);
assert(result.length == 3);