simple_moving_average.js

Array.prototype.simple_moving_average = function(window_length) {
  var averaged = new Array(this.length);
  var chunk = [];
  for (k = 0; k < this.length; k++) {
    chunk.push(this[k]);
    if (chunk.length > window_length) chunk.shift();
    averaged[k] = chunk.sum() / chunk.length; // sum() is an exercise left to the reader
  }
  return averaged;
};