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. What is the correct JSON format for a boolean value?

A) "true" or "false"

B) True or False

C) TRUE or FALSE

D) true or false

2 / 30

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

A) Functions are ignored

B) Adds null in place of functions

C) Functions are converted to strings

D) Throws an error

3 / 30

3. What does the Content-Type header specify in an API request?

A) The status of the response

B) The size of the request body

C) The HTTP method to be used

D) The format of the data being sent or expected

4 / 30

4. How do you deep clone a JSON-compatible object in JavaScript?

A) Use the clone() method

B) Use Object.assign()

C) Use JSON.clone()

D) Use JSON.stringify() and JSON.parse()

5 / 30

5. Which of these is a valid boolean value in JSON?

A) "true"

B) TRUE

C) True

D) true

6 / 30

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

A) JSONLint

B) JSON Editor Online

C) JIRA

D) Google Docs

7 / 30

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

A) Microsoft Azure

B) Amazon Web Services (AWS) CloudFormation

C) Firebase

D) DigitalOcean

8 / 30

8. What is the result of JSON.parse('null') in JavaScript?

A) Throws a syntax error

B) Returns undefined

C) Converts to the string "null"

D) Returns null

9 / 30

9. What happens if a key in a JSON object contains special characters?

A) It throws an error

B) The key must be enclosed in double quotes

C) The special characters are escaped automatically

D) The key is ignored

10 / 30

10. How are floating-point numbers represented in JSON?

A) 1.23

B) float(1.23)

C) 1.23f

D) "1.23"

11 / 30

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

A) [ "object1", "object2" ]

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

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

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

12 / 30

12. Which of these is a valid JSON array of strings?

A) [apple, banana, cherry]

B) ['apple', 'banana', 'cherry']

C) ["apple", 'banana', "cherry"]

D) ["apple", "banana", "cherry"]

13 / 30

13. Can a JSON object have duplicate keys?

A) Yes

B) Only in nested objects

C) Only in arrays

D) No

14 / 30

14. Which of these techniques can prevent excessive JSON data exposure in APIs?

A) Avoiding nested JSON structures

B) Compressing JSON

C) Using JSON.stringify()

D) Enabling strict validation in APIs

15 / 30

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

A) PostgreSQL

B) MySQL

C) MongoDB

D) SQLite

16 / 30

16. What happens when you pass a replacer function to JSON.stringify()?

A) It ensures all properties are stringified

B) It validates the JSON string

C) Throws an error if the function is invalid

D) It filters the properties to be included in the JSON string

17 / 30

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

A) Returns undefined

B) Returns null

C) Throws an error

D) Returns an empty string

18 / 30

18. Can JSON values be arrays?

A) Yes

B) Only in objects

C) No

D) Only for strings

19 / 30

19. What is JSON primarily used for?

A) Sending emails

B) Creating animations

C) Styling web pages

D) Data exchange between a client and a server

20 / 30

20. Which type of JSON structure is most efficient for transmitting data?

A) JSON with comments

B) Objects with arrays

C) Deeply nested objects

D) Flat, simple key-value pairs

21 / 30

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

A) Nested arrays

B) Functions as elements

C) Objects as elements

D) Mixed data types

22 / 30

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

A) Strings and numbers

B) Strings and booleans

C) Any data type

D) Strings only

23 / 30

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

A) Converting JavaScript objects into readable JSON format

B) Serializing objects with circular references

C) Serializing objects for storage or transmission

D) Formatting JSON output with indentation

24 / 30

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

A) Hyphen

B) Semicolon

C) Dot

D) Comma

25 / 30

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

A) Use Object.prototype.toString()

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

C) Use typeof to check if it is an object

D) Use Array.isArray()

26 / 30

26. Which of these is NOT true about JSON?

A) JSON is commonly used for APIs

B) JSON keys must always be strings

C) JSON is lightweight and language-independent

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

27 / 30

27. Which of the following is NOT valid in JSON?

A) Strings

B) Numbers

C) Boolean values

D) Comments

28 / 30

28. Which browser's developer tools are commonly used to debug JSON in web applications?

A) Safari

B) Internet Explorer

C) Firefox

D) Google Chrome

29 / 30

29. Which of the following values is not valid in JSON?

A) null

B) "Hello"

C) undefined

D) 123

30 / 30

30. What is the primary advantage of using binary JSON formats like BSON?

A) Compatibility with XML

B) Automatic validation

C) Enhanced readability

D) Smaller size and faster parsing

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