mostFrequent.js

function countOccurances(nums, k) {
  let frquencyHash = {}
  const frequencyArray = Array.from({ length: nums.length + 1 }, () => 0)

  nums.forEach(num => {
    frquencyHash[num] = (frquencyHash[num] || 0) + 1
  })

  for (const item in frquencyHash) {
    frequencyArray[frquencyHash[item]] = (
      frequencyArray[frquencyHash[item]] || []
    ).concat(item)
  }

  const sortedList = frequencyArray.sort((a,b) => b - a)

  let mostFrequent = []
  let n = 1
  while (n <= k) {
    mostFrequent = [...sortedList[n], ...mostFrequent]
    n++
  }

  return mostFrequent
}