array-iteration.md

Array Iteration with while & for

Lesson

Slides

Exercises

Try to write all of the exercises using both the for loop and while loop.

Basic Requirements

1. Write a function sum that computes the sum of the numbers in an array.

2. Write a function max that accepts an array of numbers and returns the largest number in the array.

3. Try the following at a console:

"the quick brown fox jumped over the lazy dog".split(" ");
"Hello, world!".split("")
"1,2,3,4,5,6".split(",")

What is returned by split (You can read more about it here), and how does it work?

Use split to write a function longestWord that takes a string as an argument and returns the longest word.

4. Write a function remove that accepts an array and an element, and returns an array with all ocurrences of element removed.

   function remove(array, element) {
     // your code here
   }
   remove([1, 3, 6, 2, 3], 3); // => [1, 6, 2]

5. Write a function evens that accepts an array as an argument, and returns an array consisting of all of the even numbers in that array.

More Practice

1. Write a function called average that takes an array of numbers as a parameter and returns the average of those numbers.

2. Write a function called min that finds the smallest number in an array of numbers.

3. Write a function shortestWord that works like longestWord, but returns the shortest word instead.

4. Write a function countChar that takes two arguments: any string, and a character (string of one letter), and returns the number of times that the character occurs in the string.

5. Write a function evenLengthWords that takes an array of strings as an argument, and returns an array of just the words that have an even length.

Advanced

1. Read about the join method on MDN and use it to implement a function that accepts a string as an argument and returns that string reversed.

2. Write a function keep that "keeps" certain elements in an array. The function will need to take two arguments, an array, and something else -- the second argument will be what is used to determine which elements to keep.

   You should be able to use this function to write evens, evenLengthWords, a hypothetical odds function, or oddLengthWords without changing the keep function.