Module 2: JavaScript/TypeScript

Green Boost uses TypeScript (TS) on the frontend, backend, and to define your infrastructure. The better you know TS, the better you'll be able to navigate each layer of your full stack web apps.

Learn

• JavaScript: read/scan the MDN JavaScript Guide (opens in a new tab)
  • TS is a superset of JavaScript (JS), so the better you know JS, the better you know TS.
• TypeScript: read the TypeScript Handbook (opens in a new tab)
• TypeScript Playground Examples: go to the TypeScript Playground (opens in a new tab), click on the Examples tab, and read/tinker with the preset examples covering
  • Primitives
  • Type Primitives
  • Meta-Types
  • Language
  • Language Extensions

Apply

You've been told that in addition to supporting an items table (which the template already has), you also need to support an albums table where a user can store their albums. To begin, you'll need to write use case functions to perform the basic create, read, update, and delete functions. These functions should be type-safe and performant. For now, you can use the JSONPlaceholder API (opens in a new tab) to mock your DB calls with the fake "https://jsonplaceholder.typicode.com/albums (opens in a new tab)" resource. See guide here (opens in a new tab).

M2.1 - Create Use Case

Write a core/src/modules/albums/create-album.usecase.ts file that creates an album. Albums have a userId, id, and title. Ensure the userId and id are integers and the title is no longer than 100 characters. Additionally, you must ensure the user exists before creating the album.

M2.2 - Test Function

Now test your function. Create a temporary file at core/src/modules/albums/test.ts. Import the function you created in the last step, then run pnpm tsx src/modules/albums/test.ts with your current working directory as core/. Ensure you're logging the response of the JSONPlaceholder API to ensure a "successful" creation (the API responds like you successfully created the resource even though it isn't actually created).

M2.3 - Debug Line-By-Line

Test your function with an invalid input, ensure the function throws an error with line-by-line debugging. To do this, set a breakpoint (opens in a new tab) on the line you want to begin line-by-line debugging with and then run your pnpm tsx ... command within VS Code's JavaScript Debug Terminal (opens in a new tab).

M2.4 - Other Use Cases

Create functions in a similar manner that read, update, and delete albums and then test them. Don't worry about organizing your code in a clean code architecture format like core/src/modules/item/**, we'll refactor this code in module 7.

M2.5 - Bulk Import

Now you've been tasked to create a use case function that bulk imports or creates albums. This function will accept an array of objects. The JSONPlaceholder API doesn't have a bulk create API, so you'll need to make individual requests. Make sure this function is performant by awaiting in parallel rather than serially.