ekrem-aktas

const basket = [
  { name:"apple", type: "fruit", calories: 52 }, 
  { name:"broccoli", type: "vegetable", calories: 45 },
  { name:"banana", type: "fruit", calories: 89 }
];

// Try to understand acc without looking at the last line
const { avgCalories } = basket.reduce((acc, food) => {
  if (food.type !== "fruit"){
    return acc;

ekrem-aktas

const basket = [
  { name:"apple", type: "fruit" }, 
  { name:"broccoli", type: "vegetable" }
];

// Array.reduce can be used to filter fruits
const fruits = basket.reduce((acc, food) => food.type === "fruit" ? acc.concat(food) : acc, []);

// But Array.filter is better for it
const fruits = basket.filter(food => food.type === "fruit");

ekrem-aktas

const basket = [
  { name:"apple", type: "fruit" }, 
  { name:"broccoli", type: "vegetable" }
];

// Add prices to each food in the basket
const basketWithPrices = basket.reduce((acc, food) => acc.concat({ ...food, price: getPrice(food) }), []);

// But Array.map is better for it
const basketWithPrices = basket.map(food => ({ ...food, price: getPrice(food)}));

ekrem-aktas

const numbers = [1, 2, 3];
const total = numbers.reduce((sum, num) => sum + num);

console.log(total); // 6

ekrem-aktas

const numbers = [1, 2, 3];

let total = 0;
numbers.forEach(num => total += num);

console.log(total) // 6

ekrem-aktas

const members = [["name", "apple"], ["type", "fruit"]];

const food = members.reduce((obj, [key, value]) => {
  obj[key] = value;
  return obj;
}, Object.create(null));

console.log(food); // { name: "apple", type: "fruit" }

ekrem-aktas

const members = [["name", "apple"], ["type", "fruit"]];

const obj = Object.create(null);
members.forEach(([key, value]) => obj[key] = value);

console.log(obj); // { name: "apple", type: "fruit" }

ekrem-aktas

function groupBy(arr, func){
  return arr
    .reduce((acc, item) => {
       const key = func(item);
       if (!acc[key]) {
         acc[key] = [];
       }
       acc[key].push(item);
       return acc;
    }, Object.create(null));

ekrem-aktas

function groupBy(arr, func){
  let grouped = Object.create(null);
  
  arr.forEach((item) => {
    const key = func(item);   
    if (!grouped[key]) {
      grouped[key] = [];
    }
    grouped[key].push(item);
  });

ekrem-aktas

async function validateUsername(username) {
    const errorNode = document.getElementById("error-text");

    // Check if username is a non-empty string
    if (typeof username !== "string" || username.trim() === "") {
        errorNode.innerText = "Username is required";
        return false;
    }

    // Check if username format is valid