Find's the highest values in an array and return an object with their indices as keys.

findHighest

function findHighestValues(arr, numberOfValues) {
  return Object.assign(...arr.map((val, i) => [i, val])
                             .sort((a, b) => b[1] - a[1])
                             .filter((keyVal, i) => i <= numberOfValues)
                             .map(([i, val]) => ({[i]: val})));
}