JS median and splitMedian functions

median.js

function medianSplit(array) {
  let midPoint = array.length / 2
  array = array.sort((a, b) => a - b)
  let firstHalf = array.slice(0, Math.floor(midPoint))
  let middle = array.slice(Math.floor(midPoint), Math.ceil(midPoint))[0]
  let lastHalf = array.slice(Math.ceil(midPoint), array.length)
  return [firstHalf, middle, lastHalf]
}

function median(array) {
  let [firstHalf, middle, lastHalf] = medianSplit(array)
  if (middle) return middle
  return (firstHalf[firstHalf.length - 1] + lastHalf[0]) / 2
}

// example
let [firstHalf, middle, lastHalf] = medianSplit([1, 2, 3, 4, 5, 6, 7])
let m = median([1, 2, 3, 4, 5, 6, 7])


// remove outliers using IQR (see: https://fr.mathworks.com/matlabcentral/cody/problems/42485-eliminate-outliers-using-interquartile-range)
let fullSample = [1, 2, 3, 4, 5, 6, 7]
[firstHalf, middle, lastHalf] = medianSplit(fullSample)
let interquartileRange = median(lastHalf) - median(firstHalf)
let outlierThreshhold = 1.5 * interquartileRange
let fullSampleAvg = avarage(fullSample)
let sample = fullSample.filter(p => p - fullSampleAvg <= outlierThreshhold)