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 purpose of the fetch() method in JavaScript?

A) To make HTTP requests to APIs

B) To send emails

C) To encrypt data

D) To parse JSON strings

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2. Which of these web technologies heavily relies on JSON for communication?

A) HTTP/2

B) GraphQL

C) WebSockets

D) SOAP

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3. Can JSON keys have spaces?

A) Only in arrays

B) Yes, with quotes

C) No

D) Yes, without quotes

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4. How does Elasticsearch use JSON?

A) To store and query documents

B) To validate user input

C) To render dashboards

D) To define relational tables

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

A) 123

B) undefined

C) "Hello"

D) null

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

A) To beautify JSON

B) To convert JSON into binary format

C) To replace JSON

D) To validate and secure data transmission

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

A) To reference external files

B) To include reusable schema definitions

C) To define a default value

D) To specify required properties

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8. How are elements in a JSON array separated?

A) Colons

B) Dots

C) Semicolons

D) Commas

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9. How do you reference the parent key in a deeply nested JSON object?

A) Use a library to navigate JSON paths

B) Use parent() function

C) JSON does not support parent references

D) Use key.parent

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10. How do you identify invalid JSON in a web application?

A) All of the above

B) Log errors in the console

C) Use the browser's developer tools

D) Use a linter or formatter tool

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11. What will JSON.stringify({ key: undefined }) return?

A) {}

B) {"key": "undefined"}

C) {"key": null}

D) Throws an error

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

A) null

B) []

C) ""

D) {}

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13. What is the effect of caching JSON responses?

A) Reduces server processing time for repeated requests

B) Increases JSON size

C) Prevents JSON injection attacks

D) Converts JSON to binary format

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14. What does a JSON compressor do?

A) Beautifies JSON

B) Converts JSON to XML

C) Validates JSON

D) Removes unnecessary whitespace for smaller size

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15. How can you debug a failing JSON API request in a browser?

A) Check the network tab in developer tools

B) Validate the response JSON using a linter

C) Use console.log for JSON output

D) All of the above

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16. What does the .eslintrc.json file configure in JavaScript projects?

A) Server configurations

B) Database schemas

C) Project dependencies

D) Linting rules and code quality settings

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17. Why should large JSON files be paginated in APIs?

A) To increase readability

B) To improve network performance and reduce latency

C) To reduce client-side processing time

D) To avoid key duplication

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18. How can you identify unused keys in a JSON object?

A) JSONLint

B) Postman

C) JSON Formatter

D) Static analysis tools or manual comparison

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19. How is null represented in JSON?

A) null

B) "null"

C) NULL

D) (null)

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20. Which of the following is the correct JSON format for a key-value pair?

A) {key: value}

B) {"key": "value"}

C) {key = value}

D) {"key": value}

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

A) Microsoft Azure

B) Firebase

C) Amazon Web Services (AWS) CloudFormation

D) DigitalOcean

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22. How do you merge two JSON objects?

A) Use Object.assign()

B) Use array.push()

C) Use JSON.merge()

D) Use JSON.stringify()

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23. How do you handle very large JSON data efficiently in JavaScript?

A) Split the JSON file into multiple smaller files

B) Use streaming parsers like JSONStream

C) Both B and C

D) Load the entire JSON object in memory

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24. Which keyword defines a numeric range in JSON Schema?

A) numberRange

B) minimum and maximum

C) min and max

D) range

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

A) Throws a SyntaxError

B) Returns null

C) Skips invalid parts

D) Converts to an empty object

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

A) Array

B) String

C) Date

D) Number

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28. Which of the following JSON values is equivalent to "no value"?

A) null

B) undefined

C) none

D) ""

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

A) Invalid JSON

B) Missing property name

C) SyntaxError: Unexpected token

D) Undefined object

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30. Which data structure is JSON closest to?

A) Relational tables

B) Key-value store

C) Trees

D) Arrays

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