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. Which testing tools commonly use JSON for request and response data?

A) Jenkins and Kubernetes

B) Postman and JMeter

C) Figma and Sketch

D) Selenium and Puppeteer

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

A) The client type

B) The server's API version

C) The data format expected in the response

D) The authentication type

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3. What is the correct syntax for a JSON object?

A) {key = "value"}

B) {"key": "value"}

C) [key: "value"]

D) {key: "value"}

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4. 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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5. Which keyword in JSON Schema defines the type of a value?

A) format

B) type

C) properties

D) items

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6. Which of these is valid for a JSON number?

A) 1.23

B) All of the above

C) -456

D) 123e5

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

A) JSON.decode()

B) JSON.parse()

C) JSON.stringify()

D) JSON.fetch()

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

A) Throws an error

B) {}

C) {"key": "undefined"}

D) {"key": null}

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

A) To improve network performance and reduce latency

B) To reduce client-side processing time

C) To increase readability

D) To avoid key duplication

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10. What is the effect of caching JSON responses?

A) Prevents JSON injection attacks

B) Converts JSON to binary format

C) Increases JSON size

D) Reduces server processing time for repeated requests

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11. Which keyword restricts the number of items in a JSON array?

A) minLength

B) maxSize

C) maxItems

D) arrayLimit

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

A) [1; 2; 3]

B) (1, 2, 3)

C) [1, 2, "three"]

D) {"1", "2", "3"}

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13. Can a JSON object be empty?

A) Only when nested

B) Yes

C) No

D) Only in arrays

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14. What is the result of JSON.parse('null') in JavaScript?

A) Converts to the string "null"

B) Returns null

C) Returns undefined

D) Throws a syntax error

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15. From which programming language is JSON derived?

A) Java

B) C++

C) JavaScript

D) Python

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16. Which of the following JSON strings can be parsed without error?

A) '{name: "John", age: 30}'

B) '{"name": "John", "age": 30}'

C) '{name: John, age: 30}'

D) '{"name": John, "age": 30}'

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

A) To send emails

B) To make HTTP requests to APIs

C) To encrypt data

D) To parse JSON strings

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18. What will be the result of JSON.stringify([1, 2, 3])?

A) "1,2,3"

B) Throws an error

C) [1, 2, 3]

D) "[1,2,3]"

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19. Which of the following is a common use of JSON in web development?

A) Storing and exchanging data between client and server

B) Defining CSS styles

C) Compiling JavaScript code

D) Rendering HTML elements

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20. Which character is used to enclose a JSON array?

A) ()

B) []

C) <>

D) {}

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

A) Object

B) String

C) Number

D) Array

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22. 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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23. Which function can convert an API response from JSON to JavaScript objects?

A) response.parse()

B) JSON.decode()

C) JSON.stringify()

D) response.json()

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24. Which of the following is NOT a valid use case of JSON.stringify()?

A) Serializing objects with circular references

B) Formatting JSON output with indentation

C) Serializing objects for storage or transmission

D) Converting JavaScript objects into readable JSON format

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

A) Provides a description of the schema

B) Sets a required field

C) Specifies a string pattern

D) Gives a short label to the schema or property

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26. Which of the following is NOT a valid JSON key?

A) "123name"

B) "_name"

C) "name!"

D) name

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

A) Converts JSON to XML

B) Converts an object to a string with formatting options

C) Compresses JSON output

D) Beautifies JSON output

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

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

B) [ "object1", "object2" ]

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

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

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

A) SQL Injection

B) Remote Code Execution

C) Denial of Service (DoS)

D) Cross-Site Scripting (XSS)

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

A) Storing raw event data

B) Defining UI components

C) Generating static reports

D) Compiling JavaScript files

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