JSON Quiz Test Online (30 random Questions) 2025

This quick 45-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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45 Minutes JSON Quiz Test Online

Welcome to the JSON Quiz! This quick 45-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 a common use of JSON in mobile applications?

A) Managing memory allocation

B) Defining app layouts

C) Exchanging data with remote APIs

D) Compiling source code

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

A) undefined

B) null

C) 123

D) "Hello"

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

A) Returns undefined

B) Throws a syntax error

C) Returns null

D) Converts to the string "null"

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4. Which of the following is valid JSON for a mixed data type array?

A) [ { "name": "Alice" }, 25, "true" ]

B) [ "Alice", "25", true ]

C) All of the above

D) [ "Alice", 25, true ]

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5. How do you merge two JSON objects?

A) Use array.push()

B) Use Object.assign()

C) Use JSON.stringify()

D) Use JSON.merge()

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6. How does Firebase use JSON?

A) To render user interfaces

B) For real-time database storage and synchronization

C) To define cloud functions

D) To manage authentication tokens

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7. 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

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8. Which tool is used to validate JSON syntax?

A) JSONLint

B) JSONParser

C) Postman

D) XMLParser

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9. What does the term API stand for?

A) Application Programming Interface

B) Automated Programming Integration

C) Advanced Processing Interface

D) Application Process Integration

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

A) It validates JSON schemas

B) It beautifies JSON responses

C) It makes JSON larger

D) It encrypts JSON data in transit

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

A) preferences.ini

B) config.xml

C) settings.json

D) config.txt

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

A) .xml

B) .txt

C) .js

D) .json

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14. What does JSON stand for?

A) JavaScript Online Network

B) Java Syntax Object Notation

C) Java Online Syntax Network

D) JavaScript Object Notation

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

A) To define the schema

B) To handle authentication

C) To manage subscriptions

D) To format query results

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16. How does JSON web encryption (JWE) enhance JSON security?

A) It encrypts JSON payloads for secure transmission

B) It compresses JSON data

C) It adds authentication to JSON

D) It converts JSON to binary format

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

A) Adds null in place of functions

B) Functions are ignored

C) Throws an error

D) Functions are converted to strings

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18. What type of data does a JSON object contain?

A) Only arrays

B) Only numbers

C) Key-value pairs

D) Only text

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19. What is the output of response.ok in a fetch() API call if the request is successful?

A) 1

B) true

C) "ok"

D) null

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20. 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]

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

A) Colon (:)

B) Semicolon (;)

C) Comma (,)

D) Equal sign (=)

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22. What is the default HTTP method for the fetch() function?

A) GET

B) PATCH

C) PUT

D) POST

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

A) Only an object

B) Either an object or an array

C) A string

D) Only an array

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24. What will be the output of the code: JSON.stringify({ key1: "value1", key2: function() { return "value2"; } });

A) Throws an error

B) {"key1": "value1", "key2": null}

C) {"key1": "value1", "key2": "value2"}

D) {"key1": "value1"}

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25. How are negative numbers represented in JSON?

A) [123]

B) -123

C) negative123

D) (123)

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26. Which JavaScript method can convert an object into a JSON string for an API request?

A) JSON.encode()

B) JSON.serialize()

C) JSON.parse()

D) JSON.stringify()

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27. Which of the following JSON data types is valid?

A) Object

B) String

C) All of the above

D) Float

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28. Which method is used to convert a JavaScript object into a JSON string?

A) JSON.stringify()

B) JSON.parse()

C) JSON.toString()

D) JSON.encode()

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

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

B) [ "object1", "object2" ]

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

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

30 / 30

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

A) []

B) <>

C) ()

D) {}

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