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.

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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. Can JSON arrays contain objects?

A) Yes

B) Only numbers

C) No

D) Only strings

2 / 30

2. How does HTTPS improve the security of JSON data transmission?

A) It beautifies JSON responses

B) It validates JSON schemas

C) It encrypts JSON data in transit

D) It makes JSON larger

3 / 30

3. Which of the following is the correct JSON format for a key-value pair?

A) {"key": "value"}

B) {"key": value}

C) {key: value}

D) {key = value}

4 / 30

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

A) JIRA

B) JSON Editor Online

C) JSONLint

D) Google Docs

5 / 30

5. What does a JSON array of objects look like?

A) { "array": [ "value1", "value2" ] }

B) [ { "key": "value" }, { "key": "value" } ]

C) { "object1": "value1", "object2": "value2" }

D) [ "object1", "object2" ]

6 / 30

6. Which JavaScript function converts JSON data into a format suitable for POST requests?

A) JSON.encode()

B) JSON.compress()

C) JSON.parse()

D) JSON.stringify()

7 / 30

7. Which character is used to enclose a JSON array?

A) {}

B) <>

C) ()

D) []

8 / 30

8. Which keyword specifies the schema for items in a JSON array?

A) items

B) type

C) definitions

D) properties

9 / 30

9. What is used to enclose JSON keys?

A) Parentheses

B) Double quotes

C) Single quotes

D) No quotes

10 / 30

10. Which of the following is used to validate the syntax of JSON data?

A) JSON Validator

B) JSON Formatter

C) JSON Beautifier

D) JSON Compressor

11 / 30

11. Can a JSON object have duplicate keys?

A) Only in nested objects

B) Yes

C) No

D) Only in arrays

12 / 30

12. What will JSON.stringify({ key: undefined }) return?

A) {}

B) Throws an error

C) {"key": null}

D) {"key": "undefined"}

13 / 30

13. What can be the root structure of a JSON document?

A) A string

B) Only an array

C) Either an object or an array

D) Only an object

14 / 30

14. What is the purpose of the dependencies keyword in JSON Schema?

A) To define key dependencies

B) To validate nested objects

C) To specify default values

D) To define type constraints

15 / 30

15. How are multiple key-value pairs separated in a JSON object?

A) Semicolon

B) Dot

C) Comma

D) Hyphen

16 / 30

16. What does the package.json file in a Node.js project contain?

A) Metadata about the project, dependencies, and scripts

B) The project's HTML templates

C) A list of all JavaScript files

D) The project's CSS styles

17 / 30

17. What happens if there is a syntax error in a JSON file?

A) It gets ignored

B) The JSON file still works

C) It displays a warning but continues

D) It will fail to parse

18 / 30

18. Which testing tools commonly use JSON for request and response data?

A) Jenkins and Kubernetes

B) Figma and Sketch

C) Postman and JMeter

D) Selenium and Puppeteer

19 / 30

19. Which of these is a valid JSON object?

A) {name = "John"; age = 30}

B) {"name": "John", "age": 30}

C) {name: "John", age: 30}

D) [name: "John", age: 30]

20 / 30

20. How can you format JSON output with spaces using JSON.stringify()?

A) Use JSON.prettyPrint()

B) Use the JSON.stringify(obj, null, 4) method

C) Pass a null parameter to JSON.stringify()

D) Add a spaces property to the JSON object

21 / 30

21. Which of the following is NOT a valid JSON key?

A) "name!"

B) "123name"

C) name

D) "_name"

22 / 30

22. What is the MIME type for JSON?

A) application/javascript

B) application/json

C) text/json

D) text/plain

23 / 30

23. Which of the following is an example of a nested JSON object?

A) [ "John", 30 ]

B) { "name": "John" }

C) { "name": "John", "age": 30 }

D) { "person": { "name": "John", "age": 30 } }

24 / 30

24. Which of the following is NOT a supported data type in JSON?

A) Boolean

B) Number

C) Undefined

D) String

25 / 30

25. What does the enum keyword specify in JSON Schema?

A) The maximum length of a string

B) The format of a date field

C) The default value of a property

D) A list of allowed values for a property

26 / 30

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

A) null

B) undefined

C) ""

D) none

27 / 30

27. Why should you limit the depth of nested JSON objects?

A) To improve readability

B) To remove duplicate keys

C) To prevent DoS attacks caused by deep recursion

D) To reduce data size

28 / 30

28. Which of these is a valid JSON string?

A) 'Hello, World!'

B) "Hello, World!"

C) Hello, World!

D) (Hello, World!)

29 / 30

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

A) Mixed data types

B) Objects as elements

C) Functions as elements

D) Nested arrays

30 / 30

30. What is the purpose of the space parameter in JSON.stringify()?

A) To add a specific number of spaces to the start of the output

B) To format the output with indentation

C) To add extra spacing between keys and values

D) To compress the JSON output

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