JSON Quiz Test Online (30 random Questions) 2026

This quick 30-minute challenge consists of 30 random multiple-choice questions designed to test your knowledge across various JSON topics, including the introduction to JSON, JSON syntax and basics, data types, operations in JavaScript, APIs and JSON, advanced structures, JSON Schema, tools and debugging, as well as performance and security considerations. Whether you’re new to JSON or looking to refine your skills, this quiz will enhance your understanding of JSON’s role in modern web development.

0 votes, 0 avg

You have 30 minutes to complete the quiz. The timer will start when you click the 'Start Quiz' button. Please ensure you are ready before beginning.

Time is up! Your quiz has ended. Your responses have been submitted automatically.

30 Minutes JSON Quiz Test Online

Welcome to the JSON Quiz! This quick 30-minute challenge consists of 30 random multiple-choice questions designed to test your knowledge across various JSON topics, including the introduction to JSON, JSON syntax and basics, data types, operations in JavaScript, APIs and JSON, advanced structures, JSON Schema, tools and debugging, as well as performance and security considerations. Whether you're new to JSON or looking to refine your skills, this quiz will enhance your understanding of JSON's role in modern web development.

1 / 30

1. Which messaging protocol often uses JSON for message payloads?

A) MQTT

B) FTP

C) SMTP

D) POP3

2 / 30

2. What is the primary role of JSON in GraphQL APIs?

A) To format query results

B) To handle authentication

C) To manage subscriptions

D) To define the schema

3 / 30

3. How is JSON used in data interchange for machine learning models?

A) To render visualizations

B) To serialize model configurations and results

C) To train models directly

D) To compile machine learning libraries

4 / 30

4. Why is it important to remove unused fields from JSON responses?

A) To prevent JSON schema validation errors

B) To avoid key duplication

C) To enhance JSON readability

D) To reduce payload size and improve performance

5 / 30

5. What separates two key-value pairs in a JSON object?

A) Hyphen

B) Colon

C) Semicolon

D) Comma

6 / 30

6. Which of the following is NOT a valid JSON data type?

A) Array

B) String

C) Number

D) Date

7 / 30

7. How is null represented in JSON?

A) null

B) (null)

C) NULL

D) "null"

8 / 30

8. How do you check if a given JavaScript object is a valid JSON object?

A) Use typeof to check if it is an object

B) Convert it to a string using JSON.stringify() and back using JSON.parse()

C) Use Object.prototype.toString()

D) Use Array.isArray()

9 / 30

9. How can you identify unused keys in a JSON object?

A) JSONLint

B) Static analysis tools or manual comparison

C) JSON Formatter

D) Postman

10 / 30

10. How do you handle very large JSON data efficiently in JavaScript?

A) Load the entire JSON object in memory

B) Split the JSON file into multiple smaller files

C) Both B and C

D) Use streaming parsers like JSONStream

11 / 30

11. How do you specify a format for email validation in JSON Schema?

A) validate: "email"

B) pattern: "/[email]/"

C) type: "email"

D) format: "email"

12 / 30

12. What is the difference between allOf and oneOf in JSON Schema?

A) oneOf requires at least one match, allOf requires none

B) allOf is for strings, oneOf is for arrays

C) allOf allows duplicates, oneOf does not

D) allOf validates all schemas, oneOf validates only one schema

13 / 30

13. Which online tool is commonly used to format JSON for readability?

A) JSONLint

B) GitHub

C) Visual Studio Code

D) Postman

14 / 30

14. Which database natively supports JSON as its data format?

A) MySQL

B) PostgreSQL

C) SQLite

D) MongoDB

15 / 30

15. How do you handle errors in a fetch() request?

A) Using the error property of the response

B) Errors cannot be handled in fetch()

C) Using try...catch blocks or then().catch() methods

D) Using fetchError() function

16 / 30

16. Which data structure is not directly supported by JSON?

A) Object

B) Set

C) String

D) Array

17 / 30

17. What is JSON Schema?

A) A format to store JSON data

B) A library to parse JSON data

C) A method to minify JSON files

D) A specification to define and validate the structure of JSON data

18 / 30

18. Which of the following tools allows real-time collaboration on JSON data?

A) JSON Editor Online

B) Google Docs

C) JSONLint

D) JIRA

19 / 30

19. Which of these is NOT true about JSON?

A) JSON is commonly used for APIs

B) JSON supports single-line and multi-line comments

C) JSON keys must always be strings

D) JSON is lightweight and language-independent

20 / 30

20. Which of these is NOT allowed in JSON arrays?

A) Mixed data types

B) Nested arrays

C) Functions as elements

D) Objects as elements

21 / 30

21. Which of the following JSON values is equivalent to "no value"?

A) none

B) null

C) ""

D) undefined

22 / 30

22. How do you specify that a JSON object must have at least one key in JSON Schema?

A) required: true

B) minProperties: 1

C) minKeys: 1

D) minItems: 1

23 / 30

23. Can a JSON object have duplicate keys?

A) Yes

B) Only in nested objects

C) No

D) Only in arrays

24 / 30

24. What is a safe alternative to eval() for parsing JSON in JavaScript?

A) JSON.debug()

B) JSON.minify()

C) JSON.stringify()

D) JSON.parse()

25 / 30

25. How do you merge two JSON objects?

A) Use Object.assign()

B) Use array.push()

C) Use JSON.stringify()

D) Use JSON.merge()

26 / 30

26. How are elements in a JSON array separated?

A) Dots

B) Colons

C) Commas

D) Semicolons

27 / 30

27. What is the correct syntax for a JSON object?

A) {key: "value"}

B) {key = "value"}

C) {"key": "value"}

D) [key: "value"]

28 / 30

28. How do you represent a null value in JSON?

A) "null"

B) NULL

C) (null)

D) null

29 / 30

29. Which of the following is the correct way to represent an empty JSON object?

A) {}

B) []

C) ""

D) null

30 / 30

30. How does JSON.stringify() handle functions in objects?

A) Functions are ignored

B) Throws an error

C) Functions are converted to strings

D) Adds null in place of functions

Your score is

The average score is 41%

Rate Your Experience!

Anonymous feedback

Thank you for your feedback! We appreciate your input.

10 Minutes SQL Quiz Test Online

10 Minutes JavaScript Quiz Test Online

CSS Quiz Test Online (30 random Questions)

SQL Quiz Test Online (30 random Questions)

10 Minutes MongoDB Quiz Test Online

10 Minutes Docker Quiz Test Online

Related