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

A) All of the above

B) XML

C) CSV

D) HTML

2 / 30

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

A) Array

B) String

C) Date

D) Number

3 / 30

3. What error does a missing comma between JSON key-value pairs produce?

A) Undefined object

B) Missing property name

C) Invalid JSON

D) SyntaxError: Unexpected token

4 / 30

4. What happens if you call JSON.stringify() on a Date object?

A) The date is serialized as a timestamp

B) The date is ignored

C) Throws an error

D) The date is converted to a string in ISO format

5 / 30

5. Which of the following is NOT a valid use case of JSON.stringify()?

A) Converting JavaScript objects into readable JSON format

B) Formatting JSON output with indentation

C) Serializing objects with circular references

D) Serializing objects for storage or transmission

6 / 30

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

A) minItems: 1

B) minKeys: 1

C) minProperties: 1

D) required: true

7 / 30

7. What is the purpose of the additionalProperties keyword?

A) To specify array constraints

B) To validate nested objects

C) To define extra fields that are allowed in an object

D) To allow duplicate keys in an object

8 / 30

8. What happens when you use JSON.parse() on an invalid JSON string?

A) Skips invalid parts

B) Returns null

C) Converts to an empty object

D) Throws a SyntaxError

9 / 30

9. How do you specify a pattern for a string in JSON Schema?

A) pattern

B) format

C) regex

D) match

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10. How does Postman help in debugging JSON APIs?

A) It sends requests and shows JSON responses

B) It converts JSON to XML

C) It beautifies JSON data

D) It validates JSON against schemas

11 / 30

11. Which HTTP method is commonly used to fetch JSON data from an API?

A) GET

B) POST

C) DELETE

D) PUT

12 / 30

12. What is the typical file extension for JSON files?

A) .json

B) .xml

C) .txt

D) .js

13 / 30

13. What does the title keyword do in JSON Schema?

A) Provides a description of the schema

B) Gives a short label to the schema or property

C) Specifies a string pattern

D) Sets a required field

14 / 30

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

A) {}

B) ()

C) []

D) <>

15 / 30

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

A) Semicolon

B) Colon

C) Comma

D) Hyphen

16 / 30

16. Which of the following files often uses JSON for configuration?

A) config.txt

B) config.xml

C) preferences.ini

D) settings.json

17 / 30

17. Which of the following values can be used as JSON keys?

A) Strings only

B) Any data type

C) Strings and booleans

D) Strings and numbers

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18. What is the potential issue with using eval() to parse JSON strings in JavaScript?

A) It cannot parse valid JSON strings

B) Increased memory usage

C) Vulnerability to code injection attacks

D) Slower parsing

19 / 30

19. What is a common use of JSON in analytics platforms?

A) Compiling JavaScript files

B) Generating static reports

C) Defining UI components

D) Storing raw event data

20 / 30

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

A) []

B) ""

C) {}

D) null

21 / 30

21. How can you handle errors when parsing JSON in JavaScript?

A) Using the JSON.validate() method

B) Checking the JSON string with isValid()

C) JSON parsing cannot produce errors

D) Using a try...catch block

22 / 30

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

A) Number

B) Boolean

C) Undefined

D) String

23 / 30

23. Which of the following is a commonly used library for making API requests in JavaScript?

A) Axios

B) D3.js

C) jQuery

D) Lodash

24 / 30

24. Which of these is a valid JSON string?

A) "Hello, World!"

B) 'Hello, World!'

C) (Hello, World!)

D) Hello, World!

25 / 30

25. How do you merge two JSON objects?

A) Use JSON.stringify()

B) Use Object.assign()

C) Use JSON.merge()

D) Use array.push()

26 / 30

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

A) Selenium and Puppeteer

B) Postman and JMeter

C) Figma and Sketch

D) Jenkins and Kubernetes

27 / 30

27. Can JSON objects contain duplicate keys?

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

B) Yes, with an error

C) No

D) Yes, but only for strings

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28. Which tool can be used to measure JSON parsing performance in JavaScript?

A) JSON Schema Validator

B) JSON Formatter

C) JSONLint

D) Chrome DevTools

29 / 30

29. Which JSON data type is used to represent a collection of items?

A) Number

B) Object

C) String

D) Array

30 / 30

30. Can JSON values be arrays?

A) Only in objects

B) No

C) Only for strings

D) Yes

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