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. Why is it important to validate JSON data received from external sources?

A) To prevent unexpected errors and security vulnerabilities

B) To improve parsing speed

C) To convert JSON into JavaScript objects

D) To compress JSON

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2. Can a JSON object have duplicate keys?

A) No

B) Only in nested objects

C) Yes

D) Only in arrays

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3. Which attack can occur when JSON data is excessively large and causes resource exhaustion?

A) SQL Injection

B) Cross-Site Scripting (XSS)

C) Remote Code Execution

D) Denial of Service (DoS)

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4. Can JSON objects be nested inside other JSON objects?

A) Only with strings

B) No

C) Yes

D) Only with arrays

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

A) Skips invalid parts

B) Throws a SyntaxError

C) Converts to an empty object

D) Returns null

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6. Which tool can convert a JSON file into a different format like CSV?

A) JSONLint

B) jq

C) JSON Formatter

D) Postman

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7. How can you validate JSON in a secure and efficient way?

A) Ignore validation for trusted sources

B) Manually check the JSON

C) Use custom regular expressions

D) Use a JSON Schema validator

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8. Which keyword is used to specify required fields in a JSON object?

A) required

B) fields

C) include

D) mandatory

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

A) To convert JSON into binary format

B) To beautify JSON

C) To replace JSON

D) To validate and secure data transmission

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

A) Comma

B) Hyphen

C) Dot

D) Semicolon

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11. How can JSON responses be protected from being cached by unauthorized users?

A) Minify the JSON data

B) Use the Cache-Control header with no-store

C) Use large nested objects

D) Convert JSON to XML

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12. What does the Accept header specify in an API request?

A) The data format expected in the response

B) The authentication type

C) The client type

D) The server's API version

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13. How does Postman help in debugging JSON APIs?

A) It validates JSON against schemas

B) It converts JSON to XML

C) It beautifies JSON data

D) It sends requests and shows JSON responses

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

A) Gives a short label to the schema or property

B) Specifies a string pattern

C) Provides a description of the schema

D) Sets a required field

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15. How does Elasticsearch use JSON?

A) To render dashboards

B) To validate user input

C) To store and query documents

D) To define relational tables

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16. What is a common format for API error responses?

A) JSON object

B) XML document

C) Plain text

D) CSV file

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17. Which of the following is an example of a valid JSON number?

A) 123

B) Both B and C

C) "123"

D) 123.45

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18. Why should you limit the depth of nested JSON objects?

A) To prevent DoS attacks caused by deep recursion

B) To reduce data size

C) To remove duplicate keys

D) To improve readability

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19. What does the package.json file in a Node.js project contain?

A) A list of all JavaScript files

B) The project's HTML templates

C) Metadata about the project, dependencies, and scripts

D) The project's CSS styles

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20. Which of the following is used to validate the syntax of JSON data?

A) JSON Formatter

B) JSON Validator

C) JSON Compressor

D) JSON Beautifier

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21. What is the purpose of the fetch() method in JavaScript?

A) To encrypt data

B) To send emails

C) To parse JSON strings

D) To make HTTP requests to APIs

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

A) pattern

B) format

C) match

D) regex

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

A) “Hello”

B) 'Hello'

C) Hello

D) "Hello"

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

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

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

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

D) [ "object1", "object2" ]

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25. What does the type keyword accept for mixed data types?

A) A single string

B) An array of types

C) A numeric range

D) A boolean flag

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

A) Comments

B) Strings

C) Boolean values

D) Numbers

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27. How do you represent a null value in JSON?

A) (null)

B) null

C) NULL

D) "null"

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

A) DigitalOcean

B) Amazon Web Services (AWS) CloudFormation

C) Microsoft Azure

D) Firebase

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29. What does a JSON path debugger do?

A) Extracts specific values from JSON

B) Beautifies JSON

C) Converts JSON to CSV

D) Validates JSON syntax

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30. What is JSON Schema?

A) A method to minify JSON files

B) A library to parse JSON data

C) A specification to define and validate the structure of JSON data

D) A format to store JSON data

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