Exercise Thursday

Goal: Now that we've learned about Array.prototype.map(), let's further hone our array mapping skills by completing the exercises detailed below.

Warm Up

  • What is a callback function? How is it different from a plain old function?
  • What portion of the following code is the callback function? What does this particular callback function do?
const tripledNumbers = [0,3,6,9].map(function(number) {
  return number * 3;
  • Does Array.prototype.map() alter the array it is called upon?
  • Discuss with your partner when you would use Array.prototype.forEach() and when it might be better to use Array.prototype.map().


Array Mapping Practice

Complete the following in the JavaScript DevTools console:

  • Make an array of numbers, then use Array.prototype.map() to return an array containing each of the original numbers + 1.
  • Create an array of words. Use Array.prototype.map() to return an array of the same words in all uppercase.