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. Why should large JSON files be paginated in APIs?

A) To reduce client-side processing time

B) To increase readability

C) To improve network performance and reduce latency

D) To avoid key duplication

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2. Which of these is NOT true about JSON?

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

B) JSON is lightweight and language-independent

C) JSON is commonly used for APIs

D) JSON keys must always be strings

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

A) JSON with comments

B) Objects with arrays

C) Flat, simple key-value pairs

D) Deeply nested objects

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4. How does Firebase use JSON?

A) To define cloud functions

B) To render user interfaces

C) To manage authentication tokens

D) For real-time database storage and synchronization

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5. JSON is a strict subset of which language?

A) XML

B) Python

C) SQL

D) JavaScript

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

A) To validate nested objects

B) To define key dependencies

C) To define type constraints

D) To specify default values

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

A) Defining UI components

B) Storing raw event data

C) Generating static reports

D) Compiling JavaScript files

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8. Can JSON values be functions?

A) Yes

B) Only in objects

C) Only in arrays

D) No

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9. What is JSON primarily used for?

A) Data exchange between a client and a server

B) Creating animations

C) Styling web pages

D) Sending emails

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10. Which of the following status codes indicates a successful API request?

A) 200

B) 403

C) 500

D) 404

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

A) To beautify JSON

B) To validate and secure data transmission

C) To convert JSON into binary format

D) To replace JSON

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12. 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" } }

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13. Which data structure is JSON closest to?

A) Relational tables

B) Trees

C) Arrays

D) Key-value store

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14. What happens if a JSON object has circular references when using JSON.stringify()?

A) It throws a TypeError

B) It returns an empty object

C) It skips the circular reference and continues

D) It converts successfully

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

A) To include reusable schema definitions

B) To define a default value

C) To reference external files

D) To specify required properties

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16. 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

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

A) Returns null

B) Throws an error

C) Returns undefined

D) Returns an empty string

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18. Which of the following is a valid JSON array?

A) {[1, 2, 3]}

B) [1, 2, 3]

C) (1, 2, 3)

D) <1, 2, 3>

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

A) Strings

B) Numbers

C) Comments

D) Boolean values

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20. What is the default value of additionalProperties in JSON Schema?

A) false

B) undefined

C) true

D) null

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21. Which extension helps debug JSON in Visual Studio Code?

A) Prettier

B) JSON Tools

C) REST Client

D) JSON Formatter

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22. What does a JSON compressor do?

A) Converts JSON to XML

B) Validates JSON

C) Beautifies JSON

D) Removes unnecessary whitespace for smaller size

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

A) Hyphen

B) Semicolon

C) Comma

D) Colon

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

A) Returns null

B) Throws a SyntaxError

C) Skips invalid parts

D) Converts to an empty object

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

A) "ok"

B) true

C) null

D) 1

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

A) 1.23

B) "1.23"

C) float(1.23)

D) 1.23f

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27. Which of the following data types can JSON arrays contain?

A) Mixed data types

B) Only objects

C) Only numbers

D) Only strings

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

A) Array

B) Number

C) String

D) Object

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29. What does JSON stand for?

A) JavaScript Object Notation

B) Java Syntax Object Notation

C) JavaScript Online Network

D) Java Online Syntax Network

30 / 30

30. Which of the following is a valid JSON string?

A) “Hello”

B) "Hello"

C) Hello

D) 'Hello'

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