alsciende

function interpolate(interpolation_data, new_value) {
  var keys = Object.keys(interpolation_data),
      min_value = Math.min.apply(Math, keys),
      max_value = Math.max.apply(Math, keys),
      min_image = interpolation_data[min_value],
      max_image = interpolation_data[max_value];
  return min_image + (max_image - min_image) * (new_value - min_value) / (max_value - min_value);
}

// when level = level_max, we get max PI

alsciende

function doTwoThings() {
  return new Promise(function (resolve, reject) {
    doSomething()
    .then(doSomethingElse)
    .then(resolve, reject)
  })
}