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

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• 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().

Code

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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.