JavaScript Fundamentals · Working with JSON · Lesson 35 of 48
Converting Objects to JSON with stringify
Concept
Converting Objects to JSON with stringify
JSON.stringify() turns a JavaScript object into a JSON string, which is what you send over the network or save to a file.
Any value that isn't representable in JSON — like a function, undefined, or a Symbol — is simply dropped when it's a property value during stringify.
By the end of this lesson
- Explain the core idea behind Converting Objects to JSON with stringify.
- Predict output before running a change.
- Test one realistic and one unusual input.
- Use the result to make the next decision.
How to study this page
- 1. Read one concept.
- 2. Change the example.
- 3. Run, compare, and explain.
- 4. Complete the challenge below.
Syntax
JSON.stringify(value)
JSON.stringify(value, null, 2) // pretty-printedExampleRunnable
const student = { name: "Alex", age: 20 };
const json = JSON.stringify(student);
console.log(json);Pretty-printing with indentation
const student = { name: "Alex", age: 20 };
console.log(JSON.stringify(student, null, 2));Note: The third argument to stringify controls indentation, which is handy when logging JSON for a human to read.
Self-check before continuing
Without looking at the example, describe what changes when you modify one input in Converting Objects to JSON with stringify. 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
Stringify an object representing your favorite course, then log both the object and the string to compare them.
Loading editor…
Console