Array Method Drills

Array copying I

function firstFourItems(array) {
  return array.slice(0, 4)
}

function lastThreeItems(array) {
  return array.slice(-3)
}

Array copying II

function minusLastItem(array) {
  return array.slice(0, array.length-1);
}

function copyFirstHalf(array) {
  return array.slice(0, array.length/2)
}

Squares with map

function squares(array) {
  return array.map(num => num ** 2);
}

Sort

function greatestToLeast(array) {
  return array.sort((a, b) => b - a);
}

Filter 

function shortWords(array) {
  return array.filter(function (word) {
    return word.length < 5;
  });
}

function divisibleBy5(array) {
  return array.find(num => num % 5 === 0);
}