Goal

This challenge is designed to provide additional practice with the material from Module 1. You will be creating functions that behave like common array methods.

Getting started

1. Fork and clone this repository.

2. Navigate to the cloned repository's directory on your command line. Then, run the following command:

   npm install
   

   This will install the libraries needed to run the tests.

3. Open up the repository in VSCode. Follow the instructions below to complete the Lab.

Tests

To run the tests, you can run the following command from the command line. You will need to be in the root directory of your local directory.

npm test

This will run the test output once.

Test watcher

If you'd like, you can have the tests run constantly. This means that each time you save your file, your tests will re-run. To do so, you can run the following:

npm run watch

Follow the on-screen prompts to exit out of the constant runner.

Run file

If you want to manually test out your file, you can do so by running the following command.

node index.js

The output will be printed to your terminal.

Existing files

This repository contains the following files that you may need to edit or want to take a look at:

• index.js: This is where you will write your code. This is the only file you should need to edit.
• index.test.js: All of the tests for the functions.

Tasks

After getting this repository running on your current machine, you will then need to do the following for each function:

• Complete the function so that the tests pass.
• Add and commit your changes.
• Push your code up to GitHub.

Please add and commit regularly. You should not end up with a single additional commit for this assessment.

Function descriptions

You will find examples and descriptions in both the index.js file and in the index.test.js file.

Hints

myPushFunction

• The array parameter points to the same array that was passed in. That means if you change what value is at an index on the array parameter, it will change the value of the original array (since they're the same array!).
• What index do we want to add our new value to? What if the length of the array changes?

myPopFunction

• What happens if you change the length property of an array?

myIncludesFunction

• You're going to have to check every single element to see if it's the element you're searching for.

mySliceFunction

• For this one, you are not mutating the original array. That means you'll need a new one!
• You'll need a few if checks to check if the start and index were:
  • undefined, because no value was passed in for them
  • negative
  • past the length of the array

myReverseFunction

• You can solve the tests that just ask you to return a reversed array by looping through the original array and putting them in a new array in the opposite order. But to solve the full problem, you'll have to manipulate the values at indices in the original array. Plan out (paper and pen can help here) which values will need to move to which indices.
• To swap values in two different variables (or properties, as in an array's values), you usually need a third variable to store one in temporarily.

myUnshiftFunction

• Think about what index each value moves to when adding something to the front of an array. What index does our new value go into? Where does the value that was there go to now? Paper and pen can help here as well.