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

What is the use of the $ref keyword in JSON Schema?

A) To include reusable schema definitions

B) To define a default value

C) To specify required properties

D) To reference external files

2 / 30

What does the oneOf keyword do in JSON Schema?

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

B) Validates against one specific type

C) Requires all listed schemas to match

D) Combines multiple schemas

3 / 30

How are floating-point numbers represented in JSON?

A) float(1.23)

B) 1.23

C) 1.23f

D) "1.23"

4 / 30

What happens if you call JSON.stringify() on a Date object?

A) Throws an error

B) The date is ignored

C) The date is serialized as a timestamp

D) The date is converted to a string in ISO format

5 / 30

How is JSON used in microservices architecture?

A) To exchange data between microservices

B) To compile service code

C) To define database schemas

D) To render UI components

6 / 30

What is the purpose of application/json MIME type?

A) To define JSON structure

B) To convert JSON to XML

C) To identify JSON data format

D) To parse JSON

7 / 30

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

8 / 30

What type of data does a JSON object contain?

A) Only arrays

B) Only numbers

C) Key-value pairs

D) Only text

9 / 30

Which JSON data type is used to group key-value pairs?

A) Number

B) Array

C) String

D) Object

10 / 30

JSON is a strict subset of which language?

A) JavaScript

B) SQL

C) Python

D) XML

11 / 30

How does Firebase use JSON?

A) To manage authentication tokens

B) For real-time database storage and synchronization

C) To render user interfaces

D) To define cloud functions

12 / 30

What data type is represented by {} in JSON?

A) String

B) Array

C) Null

D) Object

13 / 30

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

A) The size of the request body

B) The format of the data being sent or expected

C) The status of the response

D) The HTTP method to be used

14 / 30

JSON is _______________.

A) None of the above

B) Partially case-sensitive

C) Case-sensitive

D) Case-insensitive

15 / 30

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

A) It converts JSON to binary format

B) It encrypts JSON payloads for secure transmission

C) It compresses JSON data

D) It adds authentication to JSON

16 / 30

Can JSON values be functions?

A) Yes

B) Only in arrays

C) No

D) Only in objects

17 / 30

What does the Accept header specify in an API request?

A) The data format expected in the response

B) The client type

C) The authentication type

D) The server's API version

18 / 30

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

A) To specify data format

B) To set request priority

C) To specify the API version

D) To include authentication credentials

19 / 30

What is JSON primarily used for?

A) Data exchange between a client and a server

B) Creating animations

C) Styling web pages

D) Sending emails

20 / 30

What is the result of trying to access a non-existent key in a JSON object?

A) Returns undefined

B) Throws an error

C) Returns null

D) Returns an empty string

21 / 30

Which of the following is a valid JSON string?

A) Hello

B) 'Hello'

C) "Hello"

D) “Hello”

22 / 30

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

A) Using only numeric data

B) Removing all keys from JSON

C) Input validation and sanitization

D) Minification

23 / 30

How can you identify unused keys in a JSON object?

A) Postman

B) JSONLint

C) JSON Formatter

D) Static analysis tools or manual comparison

24 / 30

Which tool is used to validate JSON syntax?

A) Postman

B) JSONLint

C) JSONParser

D) XMLParser

25 / 30

How do you reference the parent key in a deeply nested JSON object?

A) Use a library to navigate JSON paths

B) Use key.parent

C) Use parent() function

D) JSON does not support parent references

26 / 30

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

A) Converts to an empty object

B) Returns null

C) Skips invalid parts

D) Throws a SyntaxError

27 / 30

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

A) Vulnerability to code injection attacks

B) It cannot parse valid JSON strings

C) Slower parsing

D) Increased memory usage

28 / 30

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

A) Returns null

B) Throws a syntax error

C) Converts to the string "null"

D) Returns undefined

29 / 30

What does a JSON Formatter do?

A) Parses JSON into JavaScript objects

B) Compresses JSON into a single line

C) Formats JSON into a readable and indented structure

D) Converts JSON to XML

30 / 30

How do you deep clone a JSON-compatible object in JavaScript?

A) Use the clone() method

B) Use JSON.clone()

C) Use JSON.stringify() and JSON.parse()

D) Use Object.assign()

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