no23reason

const doNTimesLoop = (n, f) => {
    for (let i = 1; i <= n; i++) {
        f(i);
    }
}

const doNTimesRec = (n, f) => {
    const body = (m) => {
        if (m > n) return;
        f(m);

no23reason

const range = require("lodash.range")
const squaresLodash = (n) => range(1, n + 1).map(
    (n) => n * n);

const squares = (n) => [...Array(n).keys()].map(
    (n) => (n + 1) * (n + 1));

console.log(squaresLodash(5)); // logs [ 1, 4, 9, 16, 25 ]
console.log(squares(5)); // logs [ 1, 4, 9, 16, 25 ]

no23reason

const squaresBad = (n) => {
    let result = [];
    for (let i = 1; i <= n; i++) {
        result.push(i * i);
    }
    return result;
}

const squares = (n) => {
    let result = new Array(n);

no23reason

const discount = (originalPrices, discountAmount) => {
    const multiplier = 1 - discountAmount;
    return originalPrices.map(price => price * multiplier);
}

const prices = [5, 25, 8, 18];
console.log(discount(prices, 0.2)); // logs [ 4, 20, 6.4, 14.4 ]

no23reason

const discount = (originalPrices, discountAmount) => {
    const multiplier = 1 - discountAmount;
    // we must clone the array
    let result = new Array(originalPrices);
    for (let i = 0; i < originalPrices.length; i++) {
        result[i] = originalPrices[i] * multiplier;
    }
    return result;
}

no23reason

const sum = (array) => array.reduce(
  (total, current) => total + current,
  0);

const numbers = [5, 25, 8, 18];
console.log(sum(numbers)); // logs 56

no23reason

const sum = (array) => {
    let result = 0;
    for (let i = 0; i < array.length; i++) {
        result += array[i];
    }
    return result;
}

const numbers = [5, 25, 8, 18];
console.log(sum(numbers)); // logs 56