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. What does the oneOf keyword do in JSON Schema?

A) Combines multiple schemas

B) Ensures that the data matches exactly one of the specified schemas

C) Validates against one specific type

D) Requires all listed schemas to match

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2. What happens when you use JSON.stringify() on an object with a circular reference?

A) It converts the object to a string successfully

B) It throws a TypeError

C) It throws a syntax error

D) It ignores the circular reference

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3. How does Postman help in debugging JSON APIs?

A) It beautifies JSON data

B) It validates JSON against schemas

C) It converts JSON to XML

D) It sends requests and shows JSON responses

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4. Which online tool is commonly used to format JSON for readability?

A) GitHub

B) Visual Studio Code

C) JSONLint

D) Postman

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5. What is the result of running JSON.parse('{"key":value}') in JavaScript?

A) SyntaxError: Unexpected identifier

B) A key-value pair object

C) ReferenceError

D) null

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

A) "123"

B) 123.45

C) Both B and C

D) 123

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

A) Invalid JSON

B) Undefined object

C) SyntaxError: Unexpected token

D) Missing property name

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

A) Metadata about the project, dependencies, and scripts

B) The project's HTML templates

C) The project's CSS styles

D) A list of all JavaScript files

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9. What is JSON primarily used for?

A) Sending emails

B) Creating animations

C) Data exchange between a client and a server

D) Styling web pages

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10. Which data structure is not directly supported by JSON?

A) String

B) Set

C) Object

D) Array

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11. Can JSON arrays contain objects?

A) Only strings

B) Yes

C) No

D) Only numbers

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12. What happens when duplicate keys are present in a JSON object?

A) The last key-value pair overrides the previous ones

B) Both key-value pairs are stored

C) The first key-value pair is ignored

D) An error is thrown

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13. What is the purpose of an API key in requests?

A) To specify the API version

B) To indicate the request priority

C) To authenticate the client

D) To encrypt the request data

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

A) Log the raw JSON data as is

B) Use a secure logging framework and mask sensitive data

C) Avoid logging altogether

D) Use JSON.stringify()

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15. Which of the following tools allows real-time collaboration on JSON data?

A) Google Docs

B) JSON Editor Online

C) JIRA

D) JSONLint

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

A) Load the entire JSON object in memory

B) Use streaming parsers like JSONStream

C) Split the JSON file into multiple smaller files

D) Both B and C

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17. What is a common vulnerability associated with parsing untrusted JSON?

A) JSON Flooding

B) JSON Parsing Loops

C) JSON Brute Force

D) JSON Injection

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18. What does the enum keyword specify in JSON Schema?

A) A list of allowed values for a property

B) The maximum length of a string

C) The format of a date field

D) The default value of a property

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

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

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

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

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

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

A) WebSockets

B) GraphQL

C) SOAP

D) HTTP/2

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

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

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

C) [ "Alice", 25, true ]

D) All of the above

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22. What is the correct JSON format for a boolean value?

A) True or False

B) TRUE or FALSE

C) true or false

D) "true" or "false"

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23. Which HTTP method is commonly used to fetch JSON data from an API?

A) PUT

B) DELETE

C) POST

D) GET

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24. What is the most efficient way to handle large JSON datasets in memory-constrained environments?

A) Load the entire JSON at once

B) Use streaming APIs to process JSON incrementally

C) Remove all nested objects

D) Convert JSON to XML first

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

A) Hyphen

B) Comma

C) Dot

D) Semicolon

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

A) Database schemas

B) Server configurations

C) Linting rules and code quality settings

D) Project dependencies

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27. Which of the following methods can help trace JSON parsing errors in JavaScript?

A) window.debug()

B) JSON.log()

C) console.parse()

D) try...catch blocks around JSON.parse()

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28. How do you access the value "Alice" from the JSON object {"name": "Alice", "age": 25}?

A) object[0]

B) object.name

C) object["Alice"]

D) object[1]

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

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

B) [ "object1", "object2" ]

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

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

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

A) Minify the JSON data

B) Use large nested objects

C) Convert JSON to XML

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

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