nawafi / amex-w04d03-map-filter-reduce

JavaScript Iterators

.map() link

Write code using .map() to have the following input and output:

• getSquares – takes in an array of numbers and returns an array of their squares

  • ex: getSquares([1, 2, 3, 4, 5]) => [1, 4, 9, 16, 25]

• isDivisibleBy3 – takes in an array of numbers and returns an array of booleans indicating whether each element is divisible by 3

  • ex: isDivisibleBy3([1, 3, 4, 6, 7, 8, 9]) => [false, true, false, true, false, false true]

.filter() link

Write code using .filter() to have the following input and output:

• getOdds – takes in an array of numbers and returns an array of only odd numbers

  • ex: getOdds([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) => [1, 3, 5, 7, 9]

• getEvens – takes in an array of numbers and returns an array of only even numbers

  • ex: getEvens([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) => [2, 4, 6, 8, 10]

• getDivisibleBy4 – takes in an array of numbers and returns an array of only numbers that are divisible by 4

  • ex: getDivisibleBy4([1, 4, 6, 8, 12, 13]) => [4, 8, 12]

.reduce() link

Write code using .reduce() to have the following input and output:

• addUpAll – add up all numbers in a given array

  • ex. addUpAll([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) => 55

• multiplyAllNums – multiply all numbers in a given array

  • ex. multiplyAllNums([1, 2, 3, 4, 5]) => 120

• squareAllNums – power up all numbers in a given array

  • ex. squareAllNums([3, 2, 3]) => 729, bc (3 ^ 2) = 9, and (9 ^ 3) = 729

• addUpAllAges – add up all the ages in an array of objects

  • ex. addUpAllAges([{name: 'Carl', age: 30}, {name: 'Cara', age: 10}, {name: 'Carmen', age: 15}]) => 55