The Shell's sorting algorithm

shellsort.js

function shellsort (arr) {
  const getGap = l => Math.floor(l / 2)
  let gap = getGap(arr.length)
  
  while ((gap = getGap(gap)) > 0) {
    for (let i = gap; i < arr.length; i++) {
      const temp = arr[i]
      
      for (var j = i; j >= gap && arr[j - gap] > temp; j -= gap)
      	arr[j] = arr[j - gap]
        
      arr[j] = temp
    }
  }
}