Async JavaScript & APIs
Understand the event loop, master callbacks/promises/async-await, and learn to talk to real HTTP APIs with fetch.
0 of 9 lessons complete
About this course
A practical, beginner-first course covering why asynchronous code exists, how the JavaScript event loop actually works, the evolution from callbacks to promises to async/await, proper error handling, what HTTP requests really are, using fetch with JSON, handling loading/error/empty UI states, and working with real-world APIs including query params, headers, rate limits and pagination.
Syllabus
The Asynchronous Model
Why JavaScript needs async code, and how the event loop, callbacks, promises and async/await fit together.
- Why Async Exists: The Event Loop in Plain EnglishLevel 1 · Complete beginner · Pass the quick check to continue12m
- Callbacks and Callback HellFinish the lesson and pass the quick check in "Why Async Exists: The Event Loop in Plain English" to unlock this lesson.12m
- Promises: A Better Way to Handle AsyncFinish the lesson, Pass the quick check and pass the coding challenge in "Callbacks and Callback Hell" to unlock this lesson.14m
- async/await: Writing Async Code That Reads Like Sync CodeFinish the lesson, Pass the quick check and pass the coding challenge in "Promises: A Better Way to Handle Async" to unlock this lesson.14m
- Error Handling in Async CodeFinish the lesson, Pass the quick check and pass the coding challenge in "async/await: Writing Async Code That Reads Like Sync Code" to unlock this lesson.14m
Talking to the Web
What HTTP requests are, how fetch works with JSON, and how to show loading/error/empty states.
- What an HTTP Request Really IsUnlimitedFinish the lesson, Pass the quick check and pass the coding challenge in "async/await: Writing Async Code That Reads Like Sync Code" to unlock this lesson.12m
- fetch() and JSONUnlimitedFinish the lesson and pass the quick check in "What an HTTP Request Really Is" to unlock this lesson.15m
Working with Real APIs
Query params, headers, rate limits, pagination, and building a small API client layer.
- Loading, Error, and Empty StatesUnlimitedFinish the lesson, Pass the quick check and pass the coding challenge in "fetch() and JSON" to unlock this lesson.12m
- Working with Real APIs: Query Params, Headers, Rate Limits, PaginationUnlimitedFinish the lesson and pass the quick check in "What an HTTP Request Really Is" to unlock this lesson.14m
- Build an API Client LayerUnlimitedComplete "Working with Real APIs: Query Params, Headers, Rate Limits, Pagination" to unlock this project.~4h