JSON Interview Questions and Answers

JSON stands for JavaScript Object Notation. It is an open-standard file format that uses human-readable text to store and transmit data objects consisting of attribute–value pairs and array data types.It is a text format that is completely language independent.

1) Mention what is JSON?

JSON is a simple data exchange format.  JSON means JavaScript Object Notation; it is language and platform independent.

2) Explain what is JSON objects?

An object can be defined as an unordered set of name/value pairs.  An object in JSON starts with {left brace} and finish or ends with {right brace}.  Every name is followed by: (colon) and the name/value pairs are parted by, (comma).


{"firstName":"John", "lastName":"Anderson"}

3) Is Json Is A Language?

JSON is a data format. It could be classified as a language, but not a programming language. Its relationship to JavaScript is that it shares its syntax (more or less) with a subset of JavaScript literals.

4) Why Json Format Is Better Than Xml?

XML is much more difficult to parse than JSON.
JSON is parsed into a ready-to-use JavaScript object.

For AJAX applications, JSON is faster and easier than XML Like mentioned in below points:

Using XML

  1. Fetch an XML document
  2. Use the XML DOM to loop through the document
  3. Extract values and store in variables

Using JSON

  1. Fetch a JSON string
  2. JSON.Parse the JSON string

5) How to convert Javascript object into Json String?

By using JSON.stringify() function we can convert  Javascript object into Json String.

Example : 

var myObj = { name: "John", age: 31, city: "New York" };
var myJSON = JSON.stringify(myObj);

6) How to Convert a string written in JSON format, into a JavaScript object?

By using JSON.parse() function we can convert Json String into Javascript Object.


var myJSON = '{"name":"John", "age":31, "city":"New York"}';
var myObj = JSON.parse(myJSON);


7) How Using JSON you can store and retrieve data into Local Storage?

When storing data, the data has to be a certain format, and regardless of where you choose to store it, text is always one of the legal formats.

JSON makes it possible to store JavaScript objects as text.


var myObj, myJSON, text, obj;

// Storing data:
myObj = { name: "John", age: 31, city: "New York" };
myJSON = JSON.stringify(myObj);
localStorage.setItem("testJSON", myJSON);

// Retrieving data:
text = localStorage.getItem("testJSON");
obj = JSON.parse(text);
document.getElementById("demo").innerHTML = obj.name;


8) What Kind Of Format Is Json, And What Does The Acronym Mean?

A lightweight data-interchange format. JavaScript Object Notation.

9) Why must one use JSON over XML?

Use JSON over XML Because:

  1. JSON doesn't use end tag
  2. JSON is shorter
  3. JSON is quicker to read and write
  4. JSON can use arrays

The biggest difference is:

 XML has to be parsed with an XML parser. JSON can be parsed by a standard JavaScript function.

10) Mention what is the function used for encoding JSON in PHP?

For encoding JSON in PHP, json_encode () function is used.  This function returns the JSON representation of a value on success or false on failure.