JavaScript Fundamentals · Working with JSON · Lesson 34 of 48
What is JSON?
Concept
What is JSON?
JSON (JavaScript Object Notation) is a lightweight, text-based format for representing data. It's the standard way APIs send and receive structured data on the web.
Despite the name, JSON is language-independent — nearly every programming language has a library for reading and writing it, which is exactly why it became the universal format for web APIs.
- Explain the core idea behind What is JSON?.
- Predict output before running a change.
- Test one realistic and one unusual input.
- Use the result to make the next decision.
- 1. Read one concept.
- 2. Change the example.
- 3. Run, compare, and explain.
- 4. Complete the challenge below.
Self-check before continuing
Without looking at the example, describe what changes when you modify one input in What is JSON?. Then reopen the editor and prove your explanation with a small test.
You are ready to continue when you can predict, test, and explain the result.
Your turn
Write a small JSON object describing a course, with title, level, and totalLessons fields.
Ask about this lesson or your next move. The guide explains the path without taking the work away from you.
Ready for the next lesson?
Mark this lesson complete when you have finished the exercise.
Console