test.js

var books = [
  {
    id: 1,
    name: 'Intro to Bash',
    description: 'A great book about bash',
    copies: 3
  },
  {
    id: 2,
    name: 'Fundamentals of Web',
    description: 'Get to grips with the fundamentals of web tech',
    copies: 1
  }
]

function getBook(id) {
  for (i = 0; i < books.length; i++) {
    if (books[i].id === id) { return books[i]; }
  }
  return undefined
}

// CASE 1
getBook(2);

// CASE 2
getBook(0);

What will be the return value in CASE 1 and CASE 2?