Calculate the Max/Min/Avg value from an array

max-min-avg.js

let collection = [1, 2, 3, 4, 5, 6, null, undefined, 7, 8, 9, 10];
collection = collection.filter(a => !!a);

let max = (prev, current)=> {
  return prev > current ? prev : current;
}

let min = (prev, current)=> {
  return prev < current ? prev : current;
}

let sum = (prev, current)=> {
  return prev + current;
}

let avg = (prev, current, index, arr)=> {
  return prev + (current / arr.length);
}

let rMax = collection.reduce(max);
let rMix = collection.reduce(min);
let rSum = collection.reduce(sum);
let rAvg = collection.reduce(avg, 0);

let rAvg2 = collection
    .map((current, i, arr) => current / arr.length)
    .reduce((prev, current)=> {
      return prev + current;
    });

Math.max(...collection);
Math.min(...collection);
Math.max.apply(null, collection);
Math.min.apply(null, collection);

console.log(rMax, rMix, rSum, rAvg, rAvg2);