Challenge 1
Parse JSON text into data
javascript
Your answer
const value = JSON.parse( );Press Ctrl⌘Enter to check your answer
Code Completion
12 Challenges
Complete the JavaScript JSON Code
Practice JSON parsing, serialization, formatting, and transformation hooks.
Advanced
~8 min read
Challenge 2
Serialize an object to JSON text
javascript
Your answer
const text = JSON.stringify(data);
// result: Press Ctrl⌘Enter to check your answer
Challenge 3
Pretty-print JSON with two-space indentation
javascript
Your answer
const text = JSON.stringify(data, null, );Press Ctrl⌘Enter to check your answer
Challenge 4
Exclude the password property
javascript
Your answer
const text = JSON.stringify(user, (key, value) => key === "password" ? undefined : value);
// complete: Press Ctrl⌘Enter to check your answer
Challenge 5
Remove a legacy property while parsing
javascript
Your answer
const value = JSON.parse(text, (key, value) => key === "legacy" ? undefined : value);
// complete: Press Ctrl⌘Enter to check your answer
Challenge 6
Parse a JSON number
javascript
Your answer
const count = JSON.parse( );Press Ctrl⌘Enter to check your answer
Challenge 7
Serialize an array
javascript
Your answer
const text = JSON.stringify( );Press Ctrl⌘Enter to check your answer
Challenge 8
Round-trip JSON-representable data
javascript
Your answer
const copy = JSON.parse(JSON.stringify( ));Press Ctrl⌘Enter to check your answer
Challenge 9
Check whether a value is a raw JSON object
javascript
Your answer
const isRaw = JSON.isRawJSON();Press Ctrl⌘Enter to check your answer
Challenge 10
Create a raw JSON value and check it
javascript
Your answer
const raw = JSON.rawJSON("42");
const isRaw = JSON.isRawJSON();Press Ctrl⌘Enter to check your answer
Challenge 11
Check that an ordinary object is not a raw JSON object
javascript
Your answer
const ordinary = { value: 42 };
const isRaw = JSON.isRawJSON();Press Ctrl⌘Enter to check your answer
Challenge 12
Check a lookalike object rather than trusting its rawJSON property
javascript
Your answer
const lookalike = { rawJSON: "42" };
const isRaw = JSON.isRawJSON();Press Ctrl⌘Enter to check your answer