JSON Quiz Test Online (30 random Questions) 2025

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 a JSON key have a number as its name?

A) No

B) Yes, without quotes

C) Only in arrays

D) Yes, with quotes

2 / 30

2. What is the output of JSON.stringify() on a nested object?

A) A deep copy of the object

B) A flattened version of the object

C) Throws an error

D) A string representation of the nested object

3 / 30

3. Can JSON arrays contain objects?

A) Yes

B) No

C) Only strings

D) Only numbers

4 / 30

4. JSON is a strict subset of which language?

A) XML

B) JavaScript

C) SQL

D) Python

5 / 30

5. Can a JSON object be empty?

A) No

B) Only in arrays

C) Only when nested

D) Yes

6 / 30

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

A) String

B) Number

C) Boolean

D) Undefined

7 / 30

7. How does Firebase use JSON?

A) For real-time database storage and synchronization

B) To render user interfaces

C) To define cloud functions

D) To manage authentication tokens

8 / 30

8. What is the MIME type for JSON?

A) application/javascript

B) text/plain

C) application/json

D) text/json

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9. What data type is represented by {} in JSON?

A) Null

B) String

C) Array

D) Object

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10. What is the use of the $ref keyword in JSON Schema?

A) To specify required properties

B) To include reusable schema definitions

C) To reference external files

D) To define a default value

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11. What will JSON.stringify(true) return?

A) true

B) Throws an error

C) "True"

D) "true"

12 / 30

12. Which of these is a valid JSON string?

A) "Hello, World!"

B) (Hello, World!)

C) Hello, World!

D) 'Hello, World!'

13 / 30

13. How do you represent a key-value pair where the value is an array?

A) { "key": "value1", "value2" }

B) [ { "key": "value1" } ]

C) { "key": [ "value1", "value2" ] }

D) { "key": { "value1": "value2" } }

14 / 30

14. Which of the following methods parses a JSON response in JavaScript?

A) JSON.decode()

B) JSON.parse()

C) JSON.fetch()

D) JSON.stringify()

15 / 30

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

A) String

B) Date

C) Array

D) Number

16 / 30

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

A) {key = "value"}

B) {key: "value"}

C) [key: "value"]

D) {"key": "value"}

17 / 30

17. Which of the following formats can JSON be easily converted into for data visualization?

A) All of the above

B) HTML

C) CSV

D) XML

18 / 30

18. Can JSON objects contain duplicate keys?

A) Yes, the last key-value pair overrides the previous ones

B) No

C) Yes, but only for strings

D) Yes, with an error

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19. What does the term API stand for?

A) Advanced Processing Interface

B) Application Programming Interface

C) Automated Programming Integration

D) Application Process Integration

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20. In which cloud service is JSON commonly used for defining infrastructure as code?

A) DigitalOcean

B) Amazon Web Services (AWS) CloudFormation

C) Microsoft Azure

D) Firebase

21 / 30

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

A) required: true

B) minItems: 1

C) minKeys: 1

D) minProperties: 1

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22. Can a JSON object have duplicate keys?

A) No

B) Only in arrays

C) Yes

D) Only in nested objects

23 / 30

23. How does Elasticsearch use JSON?

A) To validate user input

B) To render dashboards

C) To store and query documents

D) To define relational tables

24 / 30

24. What is the purpose of using JSON Web Tokens (JWT)?

A) To convert JSON into binary format

B) To replace JSON

C) To beautify JSON

D) To validate and secure data transmission

25 / 30

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

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

B) Use JSON.prettyPrint()

C) Add a spaces property to the JSON object

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

26 / 30

26. What is the result of trying to access a non-existent key in a JSON object?

A) Returns null

B) Returns undefined

C) Returns an empty string

D) Throws an error

27 / 30

27. What symbol is used to enclose a JSON array?

A) []

B) {}

C) <>

D) ()

28 / 30

28. What is the effect of caching JSON responses?

A) Converts JSON to binary format

B) Prevents JSON injection attacks

C) Increases JSON size

D) Reduces server processing time for repeated requests

29 / 30

29. What does a 404 status code signify in an API response?

A) Unauthorized access

B) Bad request

C) Internal server error

D) Resource not found

30 / 30

30. What does the Content-Security-Policy header do for JSON responses?

A) Defines the format of JSON data

B) Restricts where JSON can be loaded from to prevent cross-site scripting (XSS) attacks

C) Specifies how JSON is cached

D) Ensures JSON is minified

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