Test reduce function https://evertpot.com/no-reduce/

use-reduce.js

const callbackFunction1 = function(
    accumulator,
    currentElement,
    currentIndex,
    array
) {
    // Get the maximum by checking first if there is a maximum from the previous step
    const maximum = accumulator.maximum
        ? // If there is, then check if the current element is higher than the previous maximum
          accumulator.maximum < currentElement
            ? currentElement
            : accumulator.maximum
        : // If there isn't, use the current element right away
          currentElement;

    // Get the minimum by checking first if there is a minimum from the previous step
    const minimum = accumulator.minimum
        ? // If there is, then check if the current element is lower than the previous maximum
          accumulator.minimum > currentElement
            ? currentElement
            : accumulator.minimum
        : // If there isn't, use the current element right away
          currentElement;

    // Get the average by checking if we're at the last step (where it we can finally calculate the average)
    const average =
        currentIndex === array.length - 1
            ? (accumulator.average + currentElement) / array.length
            : // If we're not at the last step, check if there even is a value from the previous step
            accumulator.average
                ? accumulator.average + currentElement
                : currentElement;

    // Return the value for the next element
    return {
        maximum,
        minimum,
        average
    };
};

const getArrayStats1 = function(input) {
    return input.reduce(callbackFunction1, {})
};

// =========================================================================================================

const callbackFunction2 = function(
    accumulator,
    currentElement,
    currentIndex,
    array
) {
    // Check if the current element is first element
    return currentIndex === 0
    ? {
        maximum: currentElement,
        minimum: currentElement,
        sum: currentElement
    }
    : {
        // Check if the current element is higher than the previous maximum
        maximum: accumulator.maximum < currentElement ? currentElement : accumulator.maximum,
        // Check if the current element is lower than the previous maximum
        minimum: accumulator.minimum > currentElement ? currentElement : accumulator.minimum,
        sum: accumulator.sum + currentElement
    };
};

const getArrayStats2 = function(input) {

    if (input.length === 0) return {};

    const result = input.reduce(callbackFunction2, {});

    return {
        maximum: result.maximum,
        minimum: result.minimum,
        average: result.sum / input.length
    };
};

// ========================================================================================================

const getArrayStats3 = function(input) {

    if (input.length === 0) return {};

    let maximum = input[0];
    let minimum = input[0];
    let sum = 0;
    for(const item of input) {
        maximum = item > maximum ? item : maximum;
        minimum = item < maximum ? item : minimum;
        sum += item;
    }

    const average = sum / input.length;

    return {
      maximum,
      minimum,
      average
    };
};

// =========================================================================================================
const createRandomArray = function(length, max) {
    return Array.from({length}, () => Math.floor(Math.random() * max));
};



// Data
const data = createRandomArray(10, 10000);

// Test 1
const time1 = {start: 0, end: 0, run: 0};
time1.start = process.hrtime.bigint();
const result1 = getArrayStats1(data);
time1.end = process.hrtime.bigint();
time1.run = time1.end - time1.start;

// Test 2
const time2 = {start: 0, end: 0, run: 0};
time2.start = process.hrtime.bigint();
const result2 = getArrayStats2(data);
time2.end = process.hrtime.bigint();
time2.run = time2.end - time2.start;

// Test 3
const time3 = {start: 0, end: 0, run: 0};
time3.start = process.hrtime.bigint();
const result3 = getArrayStats3(data);
time3.end = process.hrtime.bigint();
time3.run = time3.end - time3.start;

console.log(result1, time1);
console.log(result2, time2);
console.log(result3, time3);
console.log(data);