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 a safe alternative to eval() for parsing JSON in JavaScript?

A) JSON.parse()

B) JSON.stringify()

C) JSON.minify()

D) JSON.debug()

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

A) The format of the data being sent or expected

B) The size of the request body

C) The HTTP method to be used

D) The status of the response

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3. Which method can be used to transform a JSON object into an iterable array?

A) Object.keys()

B) All of the above

C) Object.entries()

D) Object.values()

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4. From which programming language is JSON derived?

A) C++

B) Python

C) Java

D) JavaScript

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5. What is the potential issue with using eval() to parse JSON strings in JavaScript?

A) Vulnerability to code injection attacks

B) Increased memory usage

C) It cannot parse valid JSON strings

D) Slower parsing

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

A) A list of all JavaScript files

B) The project's CSS styles

C) The project's HTML templates

D) Metadata about the project, dependencies, and scripts

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7. What is the typical file extension for JSON files?

A) .json

B) .txt

C) .xml

D) .js

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8. Which of the following is an invalid JSON structure?

A) { "key": [1, 2, { "nested": "value" }] }

B) { "key": "value", "key": "anotherValue" }

C) { "key": { "nested": { "deep": [1, 2] } } }

D) [ { "key1": "value1" }, { "key2": "value2" } ]

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

A) true

B) null

C) "ok"

D) 1

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10. Which of the following formats can JSON be easily converted into for data visualization?

A) CSV

B) XML

C) HTML

D) All of the above

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

A) WebSockets

B) HTTP/2

C) SOAP

D) GraphQL

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12. What is the primary function of JSON.stringify(value, replacer, space)?

A) Converts an object to a string with formatting options

B) Beautifies JSON output

C) Converts JSON to XML

D) Compresses JSON output

13 / 30

13. Which tool can be used to measure JSON parsing performance in JavaScript?

A) JSONLint

B) JSON Formatter

C) JSON Schema Validator

D) Chrome DevTools

14 / 30

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

A) It adds authentication to JSON

B) It encrypts JSON payloads for secure transmission

C) It converts JSON to binary format

D) It compresses JSON data

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15. What is the best approach to log sensitive information within JSON responses?

A) Avoid logging altogether

B) Use JSON.stringify()

C) Use a secure logging framework and mask sensitive data

D) Log the raw JSON data as is

16 / 30

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

A) “Hello”

B) "Hello"

C) 'Hello'

D) Hello

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

A) Compressing JSON

B) Enabling strict validation in APIs

C) Using JSON.stringify()

D) Avoiding nested JSON structures

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

A) It ensures all properties are stringified

B) Throws an error if the function is invalid

C) It validates the JSON string

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

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

A) String

B) Float

C) Object

D) All of the above

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21. What does a JSON compressor do?

A) Validates JSON

B) Removes unnecessary whitespace for smaller size

C) Beautifies JSON

D) Converts JSON to XML

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22. Which of the following methods parses a JSON response in JavaScript?

A) JSON.parse()

B) JSON.stringify()

C) JSON.decode()

D) JSON.fetch()

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

A) A numeric range

B) A boolean flag

C) An array of types

D) A single string

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

A) {}

B) null

C) []

D) ""

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25. What is the purpose of the additionalProperties keyword?

A) To allow duplicate keys in an object

B) To validate nested objects

C) To specify array constraints

D) To define extra fields that are allowed in an object

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26. What is the purpose of JSON in REST APIs?

A) To validate API responses

B) To render HTML pages

C) To define API endpoints

D) To structure and exchange data between client and server

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

A) JSON Formatter

B) JSON Compressor

C) JSON Beautifier

D) JSON Validator

28 / 30

28. What is used to enclose JSON keys?

A) Double quotes

B) No quotes

C) Parentheses

D) Single quotes

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29. What is the maximum depth for nesting in JSON?

A) Depends on the programming language and environment

B) 5 levels

C) 10 levels

D) Unlimited

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30. What does the JSON.parse() method do in JavaScript?

A) Validates a JSON string

B) Converts a JSON string into a JavaScript object

C) Parses a JSON string into an XML object

D) Converts a JavaScript object into a JSON string

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