Table of Contents

1. Challenge

   Introduction

   Welcome to Guided: Implement Interfaces, Enums, and Type Guards in TypeScript - Geometry Helper Part 2. This is the second lab in a two-lab series in which you will be implementing a library for performing geometric calculations using Typescript.

   In this part of the series, you will be using structures such as enums, interfaces, and type guards to implement calculations involving 2D points.

   Finally, you will be exporting and importing your library to be used within the main application. If you are stuck at any time, feel free to take a look at the solution directory.

   The application will throw errors when run until you complete the lab. Once completed, it should work correctly.

   How to Run the App:

   The application can be started by clicking the Run button in the Terminal or by running the command npm start in the Terminal.

2. Challenge

   Step 1: Implementing Types

   First, you will need to define a few structures for handling the calculations between 2D points.

   A LineType enum, or set of constant values, is useful here for determining the type of the line formed between two points. A Point interface is necessary here to specify the structure of a 2D point. In this case, it will just be an object with x and y properties as numbers.

   Finally, a type guard is useful to verify that a specified object correctly implements the Point interface. In other words, it will verify that an object is indeed a Point. This will be necessary for validating inputs in the main app.ts file.

3. Challenge

   Step 2: Implementing Point Calculations

   Now that you've defined LineType, Point, and the isPoint type guard, you'll now need to implement functions for 2D point calculations. These include slope, distance, midpoint, and the equation of a line passing through two given points.

   All of these functions will take two Point parameters, which allow any object that implements the Point interface. They will then return a string or number by calculating the specified value using the x and y coordinates of the two given Point parameters.

4. Challenge

   Step 3: Exporting and Importing

   Finally, you'll need to import your types and calculation functions into index.ts and re-export them for use in app.ts just like you did in part 1 of this lab.

   This time, you'll have many more types and functions prefaced with the export keyword in their individual files. This can make importing in index fairly verbose, so instead you can just import the file in index with a statement such as import filepath.

   Re-exporting everything from this import typically follows the syntax export * from filepath. All done! You can now run the application by clicking the Run button in the Terminal.

   When executed, the application will prompt you for the calculations you'd like to perform (including the shapes from part 1) before asking you to input your desired values.

   Once entered, it will display the results from the calculations using the functions you implemented!