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

Which of the following is a valid JSON string?

A) "Hello"

B) “Hello”

C) 'Hello'

D) Hello

2 / 30

What is a common use of JSON in mobile applications?

A) Managing memory allocation

B) Defining app layouts

C) Compiling source code

D) Exchanging data with remote APIs

3 / 30

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

A) JSON.decode()

B) response.parse()

C) JSON.stringify()

D) response.json()

4 / 30

Which of these is NOT a valid JSON value?

A) A function

B) A boolean

C) A null value

D) A string

5 / 30

Which of the following files often uses JSON for configuration?

A) config.txt

B) config.xml

C) settings.json

D) preferences.ini

6 / 30

What type of data does a JSON object contain?

A) Only text

B) Only numbers

C) Only arrays

D) Key-value pairs

7 / 30

What is the default HTTP method for the fetch() function?

A) PUT

B) GET

C) PATCH

D) POST

8 / 30

What separates two key-value pairs in a JSON object?

A) Colon

B) Hyphen

C) Semicolon

D) Comma

9 / 30

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

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

B) [ "Alice", 25, true ]

C) All of the above

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

10 / 30

JSON is _______________.

A) Case-sensitive

B) Partially case-sensitive

C) Case-insensitive

D) None of the above

11 / 30

What does a 404 status code signify in an API response?

A) Bad request

B) Resource not found

C) Internal server error

D) Unauthorized access

12 / 30

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

A) It throws a TypeError

B) It throws a syntax error

C) It converts the object to a string successfully

D) It ignores the circular reference

13 / 30

What is the difference between allOf and oneOf in JSON Schema?

A) allOf allows duplicates, oneOf does not

B) allOf is for strings, oneOf is for arrays

C) allOf validates all schemas, oneOf validates only one schema

D) oneOf requires at least one match, allOf requires none

14 / 30

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

A) JSON.parse()

B) JSON.debug()

C) JSON.stringify()

D) JSON.minify()

15 / 30

Which of the following is NOT a supported data type in JSON?

A) Boolean

B) Undefined

C) Number

D) String

16 / 30

How can you handle errors when parsing JSON in JavaScript?

A) JSON parsing cannot produce errors

B) Using a try...catch block

C) Using the JSON.validate() method

D) Checking the JSON string with isValid()

17 / 30

How do you check if a given JavaScript object is a valid JSON object?

A) Use Object.prototype.toString()

B) Convert it to a string using JSON.stringify() and back using JSON.parse()

C) Use Array.isArray()

D) Use typeof to check if it is an object

18 / 30

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

A) Enabling strict validation in APIs

B) Using JSON.stringify()

C) Avoiding nested JSON structures

D) Compressing JSON

19 / 30

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) Load the entire JSON object in memory

D) Both B and C

20 / 30

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

A) JSON Editor Online

B) JIRA

C) JSONLint

D) Google Docs

21 / 30

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

A) GraphQL

B) SOAP

C) HTTP/2

D) WebSockets

22 / 30

Which of the following status codes indicates a successful API request?

A) 200

B) 500

C) 403

D) 404

23 / 30

What is the primary role of JSON in GraphQL APIs?

A) To handle authentication

B) To manage subscriptions

C) To format query results

D) To define the schema

24 / 30

What does a JSON compressor do?

A) Removes unnecessary whitespace for smaller size

B) Validates JSON

C) Beautifies JSON

D) Converts JSON to XML

25 / 30

Which of the following is a valid JSON array?

A) (1, 2, 3)

B) {[1, 2, 3]}

C) [1, 2, 3]

D) <1, 2, 3>

26 / 30

What is the purpose of the Authorization header in API requests?

A) To include authentication credentials

B) To specify data format

C) To set request priority

D) To specify the API version

27 / 30

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

A) mandatory

B) required

C) include

D) fields

28 / 30

Which HTTP method is typically used for sending data to an API?

A) GET

B) POST

C) OPTIONS

D) DELETE

29 / 30

Which of the following ensures JSON data is safe from injection attacks?

A) Removing all keys from JSON

B) Input validation and sanitization

C) Minification

D) Using only numeric data

30 / 30

What does the oneOf keyword do in JSON Schema?

A) Combines multiple schemas

B) Validates against one specific type

C) Requires all listed schemas to match

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

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