Top JSON Interview Questions and Answers

List of most popular JSON interview questions and answers to help you prepare for the upcoming interview:

Before proceeding to these questions and answers, please have a quick look at our previous JSON tutorials.

We have some comprehensive tutorials in detail about JSON and the ways to create them programmatically. We hope our series of JSON tutorials will be of immense help to enrich your knowledge.

Quiz on JSON Interview Questions: Test Your JSON Skills Now

Take up this quick challenge to test your JSON Skills. This quiz on JSON interview questions is perfect for Web Developers, API Developers, or Front-end Engineers who are preparing for any JSON-focused technical interview.

Basic JSON Interview Questions for Developers

Q #1) What is JSON? Explain.

Answer: JSON is an abbreviation of JavaScript Object Notation. It is one of the simplest data interchange formats, independent of programming language and platform. Its lightweight text-based structure makes it easily readable. It is derived from JavaScript for presenting simple data as key-value pairs.

It is often used for serialization and transmission of data between network connections. It is mostly used for data transmission between a web application and the server, thereby making it a popular alternative to the XML format.

Q #2) Who is known as the father of JSON?

Answer: Douglas Crockford is known as the father of JSON. Douglas Crockford was the person who originally defined the JSON format back in 2000.

Q #3) Do all programming languages and platforms support JSON?

Answer: Yes, most of the technologies that work with data transmission between the systems support JSON format. Due to its text-based nature, nearly all programming languages and platforms can support JSON. These include JavaScript, C, C++, C#, Perl, Java, Python, PHP, etc.

Q #4) What is meant by JSON objects?

Answer: An object is defined as a set of key-value pairs. A JSON starts with a left brace “{“ and ends with another right brace “}”. Every key is followed by a colon “:” and the key-value pairs are separated from each other using a comma “,”. So, the JSON object is a collection of keys along with their values arranged in a pre-specified JSON format.

Q #5) What is the extension of the JSON file?

Answer: A JSON file has an extension of “.json”. Being in a text-based format, a JSON file can be viewed or edited using any text editor, like Notepad or Notepad++.

Q #6) Explain in detail the advantages and features of JSON?

Answer: JSON structure possesses numerous advantages over other data interchange formats. They are:

• Easy to use and fast in nature. JSON syntax offers easy parsing of data and even faster implementation. The lightweight structure of JSON allows it to respond much faster rate.
• It is compatible with numerous operating systems and browsers. This allows JSON schema to be attuned to many platforms without any extra effort to make sure it’s compatible with other platforms.
• It supports a wide range of data types, including integers, doubles, strings, Booleans, and more.

Q #7) What are the limitations of JSON?

Answer: JSON is one of the most popular data interchange formats available in today’s scenario. It has several advantages over the other formats, but it also has its own set of limitations too. They are:

• As the data gets complex with several nested or hierarchical structures, it becomes complex for human readability.
• JSON is not suitable for handling very complex, large data.
• JSON doesn’t have support for handling multimedia formats such as rich text or images.
• It doesn’t support comments.

Q #8) What are the uses of JSON?

Answer: JSON is mainly used for data interchange between the two systems.

• JSON is used prominently for the transmission of serialized data over a network connection between two systems.
• APIs and web services use JSON to format and transfer data.
• Most modern programming languages can be used with JSON.
• JSON can be used with JavaScript applications such as browser plugins and websites.
• JSON can be used to read data from the web server and display data on the web pages.

Q #9) Explain JSON syntax rules.

Answer: Several rules describe the structure of the JSON.

These are:

• Data inside a JSON is arranged in key-value pairs. The left side represents the key, and the data on the right side represents the value. A colon separates both key and value “:”.
• Each set of key-value pairs is separated from the other pairs by using a comma “,”.
• Curly braces define the JSON objects. The left curly brace “{“ represents the start of the object, and the right curly brace “}” represents the end of an object.
• Arrays are defined within a JSON object by using square brackets “[ ]”.

Q #10) What are the advantages of JSON over XML?

Answer: JSON has emerged as one of the most popular data interchange methods. It has several advantages over XML that help it replace XML as the most popular data transfer format.

• JSON is lighter and faster than XML.
• JSON has object types, but XML doesn’t define objects as types. JSON has different object types for different sets of data, such as string, integer, boolean, array, etc. All XML objects are categorized as just one data type, i.e., string.
• JSON data can be easily accessed as a JSON object using JavaScript. The XML data needs to be parsed and allocated to the variables using APIs. Getting value out of a JSON is as easy as reading an object in your JavaScript programming.

This text-based, lightweight nature makes JSON more accessible and useful than XML.

JSON Scenario-Based Interview Questions

Q #11) What are the similarities between JSON and XML?

Answer: Several similarities can be found between JSON and XML. They are:

• Both JSON and XML are used to transfer data between different systems.
• Both JSON and XML have a simple structure and are readable by humans.
• Both are independent of programming language.
• Both JSON and XML support nested or hierarchical structures.
• Both of these can be parsed easily through several programs.
• Both these structures have support for Unicode.

Q #12) Name the browsers that support JSON format.

Answer: Support for JSON is included in almost all the new versions of the browsers. Internet Explorer, Chrome, Safari, Mozilla Firefox, etc., all support JSON format.

Q #13) Explain the use of the NewtonSoft framework Net.

Answer: Json.net or Newtonsoft is one of the most popular frameworks used in .NET for performing operations with JSON.

• It enables users to parse, create, modify, and query JSON using its internal framework objects such as JArray, JValue, JObject, etc.
• It provides an easier solution for querying JSON with a syntax similar to XPath.
• It enables the user to serialize or deserialize any objects in .NET with its great JSON serializer.
• It is faster than contemporary serializers.
• Easy to use and simple.
• It also supports conversion from XML to JSON or vice versa.
• One of the most important features is its free and open-source nature.

Q #14) How to use Newtonsoft or JSON.net for serializing JSON data?

Answer: Newtonsoft or JSON.net is one of the most widely used frameworks for serializing and deserializing JSON structures in a .NET environment.

To start converting the data into a JSON structure, we need to create an object to store the data.

Car car = new car();

Once we have created a new object, we can define/store the keys and variables in that object.

car.Brand = "Hyundai";
car.Name = “Verna”;
car.Color = “Red”;

Once all the data is stored in the defined object, then we can serialize it using SerializeObject.

string json = JsonConvert.SerializeObject(car);

The JSON structure will be stored in the string defined. The structure will be something like this:

{
"Brand":"Hyundai",
"Name": "Verna",
"Color": “Red”
}

Q #15) How to use Newtonsoft or JSON.net for deserializing the JSON data?

Answer: Newtonsoft also provides functionality for deserializing the JSON structure to retrieve the data. The deserialization process is just the reverse of serialization. Here, the same steps are followed but in reverse order.

At first, we need to store the JSON that we want to deserialize in a string.

string JSON = @"{
"Brand": "Hyundai",
"Name": "Verna",
"Color": “Red”
}

Once we have stored the JSON structure in a string, we will use the following command to deserialize it and receive different data.

Car m = JsonConvert.DeserializeObject<Car>(JSON);

Now, we will retrieve all the data from the JSON list one by one.

string Brand = m.Brand;
string Name = m.Name;
string Color = m.Color;

Q #16) Can a comment be added inside a JSON file?

Answer: As per the structure, JSON doesn’t support any comments. However, a Key or data object can hold your comments. We need to make sure that during the processing of the JSON, your application ignores the given data element.

Q #17) Name some of the most widely used libraries in .net for JSON.

Answer: There are several popular libraries available for JSON in .net. Some of them are:

• Newtonsoft: It is one of the most widely used frameworks for converting using C#. It is quite famous because of its flexibility and performance. It also supports JSON to XML conversion.
• DataContractJsonSerializer: This is the built-in library provided by Microsoft for handling JSON objects within the .net environment.

Q #18) What is the use of JSON.parse in JavaScript?

Answer: It is used to parse the data present inside the JSON into objects for using its values.

The syntax used to parse JSON data:

string json = ‘{
"Brand": "Hyundai",
"Name": "Verna",
"Color": “Red”
}’
var obj = JSON.parse(json);

This will convert JSON data into an object from which we can retrieve the data for use with the application.

Q #19) Explain JSONP in simple language.

Answer: JSONP is also known as JSON with Padding. It is a communication technique used by JavaScript programs to call data from a server that is present in a domain, which is different from that of the client. JSONP allows users to share data without the restriction of the cross-domain or same-origin policy of the system and the environment.

Q #20) What are the limitations of JSONP?

Answer: JSONP is used to bypass the same-origin policy of web browsers. It may seem like a perfect way to get around the restriction, but it has its own set of limitations as well.

They are:

• As all the JSONP calls are made by including a <script> tag, the request made is confined only to the GET method.
• It cannot be used for POST or PUT requests.
• It can be used only for read-only services and APIs.

Final Thoughts on JSON Frontend Interview Questions

This was the list of the most frequently asked questions related to JSON. All the questions and answers provided in this tutorial have been explained in the JSON tutorials published earlier.

Hence, we recommend you start your learning by going through the tutorials first.

Hope this tutorial will help you clear the JSON interview successfully.