JavaScript Fundamentals: Arrays Lab

Learning Goals

• Practice writing arrays
• Practice manipulating arrays

Introduction

We've seen how arrays can be created and manipulated. Now we can practice putting it all together. To recap, push() pushes elements onto the ends of arrays, and pop() pops them off; similarly, unshift() adds elements to the beginnings of arrays, and shift() pulls them off. Now it's time to practice what we've learned.

Practice Writing Arrays

We're going to work with actions that mutate ("change") their underlying structures (like pop(), push(), shift(), and unshift()).

Generally, it's good practice to avoid mutating a program's state whenever possible. However, for now, we're going to focus on the fundamentals of working with Arrays.

1. Run learn.
2. Read the errors; vocalize what they're asking you to do.
3. Write code; repeat steps 1 and 2 often until a test passes.
4. Repeat as needed for further tests.
5. Run learn submit when finished!

First, we're going to create four arrays of pets. Define 4 const called: append, prepend, removeLast and removeFirst, and set all to an initial value of ["Milo", "Otis", "Garfield"]. These are the arrays that we'll work with for each exercise.

NOTE: "Append" means "add to the end" and "prepend" means "add to the beginning."

Practice Manipulating Arrays

1. Append the pet "Odie" to the end of append.
2. Prepend the pet "Odie" to the beginning of prepend.
3. Remove the last pet from removeLast.
4. Remove the first pet from removeFirst.

Conclusion

We put our array knowledge into practice by writing and manipulating arrays. We also covered the concept of mutating state.