Functions Lab (90 mins)

Pre-requisites:*

• Differentiate between data types (strings, numbers, Booleans).
• Use if/else if/else conditionals to control program flow based on Boolean conditions.
• Create and manipulate arrays.
• Use loops to iterate through the elements in an array.
• Describe why functions are useful.
• Describe how parameters relate to functions.
• Explain how return statements are used in JavaScript.

Introduction

Let's practice writing some functions!

Exercise

Requirements

Follow the requirements in the list below:

1. Define a function maxOfTwoNumbers that takes two numbers as arguments and returns the largest of them. Use the if-then-else construct available in JavaScript. Do some Googling to figure this out if you forget how conditionals work.
2. Define a function maxOfThree that takes three numbers as arguments and returns the largest of them.
3. Write a function isCharacterAVowel that takes a character (i.e., a string of length 1) and returns true if it is a vowel and false otherwise.
4. Define a function sumArray and a function multiplyArray that sums and multiplies (respectively) all the numbers in an array of numbers. For example, sumArray([1,2,3,4]) should return 10, and multiplyArray([1,2,3,4]) should return 24.
5. Write a function that returns the number of arguments passed to the function when called.
6. Define a function reverseString that reverses a string. For example, reverseString("jag testar") should return the string "ratset gaj".
7. Write a function findLongestWord that takes an array of words and returns the length of the longest word in the array.
8. Write a function filterLongWords that takes an array of words and a number i and returns a new array of words that are longer than i characters long.

Bonus For this bonus, you'll have to do some research on objects.

1. Write a function that takes a string as an argument and returns an object where:

• The keys are the characters that occur in the string.
• The values are the number of occurrences for each letter, regardless of the case.

For example, calling the function with the string "General Assembly" will return:

{
  a: 2,
  b: 1,
  e: 3,
  g: 1,
  l: 2,
  m: 1,
  n: 1,
  r: 1,
  s: 2,
  y: 1
}

Starter Code

Open the file main.js. All the function names are already inside the file; you just need to implement the functions by adding code inside each one.

OPTION 1:

Copy/paste contents of main.js into replit and work through the problems there.

Option 2:

Use the Chrome Dev Tools console to practice executing your code.

Option 3:

Alternately, you can add console.log(); statements in your main.js file; then you should see the values displayed in the console when you open the index.html file in your browser.

ADDITIONAL RESOURCES

• Readings
  • MDN Functions