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Practice

JSON (JavaScript Object Notation)

JSON (JavaScript Object Notation) is a data interchange format for storing and exchanging information.

The format represents data using curly braces { } or square brackets [ ], consisting of key-value pairs. The keys are wrapped in double quotes with values made up of strings, numbers, etc.

JSON Example
{
  "name": "CodeFriends",
  "address": {
    "city": "New York"
  },
  "age": 20
}

Commas (,) are used to separate multiple key-value pairs within an object, but no comma should follow the last key-value pair.

Although JSON is based on the way JavaScript creates objects, it is language-independent and can be used with most programming languages.

It is widely used for data interaction between servers and web pages in most applications.


Basic Structure of JSON​

JSON can only be expressed as an object or an array.


1. Object​

A collection of key-value pairs wrapped in curly braces { }.

JSON Object Format
{
    "Key1": "Value1",
    "Key2": "Value2",
    ...
}
JSON Object Example
{
  "name": "CodeFriends",
  "age": 25
}

2. Array​

A list of values wrapped in square brackets [ ].

JSON Array Format
["Value1", "Value2", "..."]
JSON Array Example
["Apple", "Banana", "Cherry"]

Handling JSON in JavaScript​

JavaScript provides a built-in JSON object to handle JSON data.

The JSON object has methods to convert JSON data into a string or a JavaScript object.


1. JSON.stringify()​

Converts JavaScript objects or values into a JSON string.

Example: JSON.stringify()
const obj = {
  name: 'CodeFriends',
  age: 25,
};

const jsonString = JSON.stringify(obj);
console.log(jsonString); // '{"name":"CodeFriends","age":25}' output

2. JSON.parse()​

Converts a JSON string back into a JavaScript object or value.

Example: JSON.parse()
const jsonString = '{"name":"CodeFriends","age":25}';

const obj = JSON.parse(jsonString);
console.log(obj.name); // "CodeFriends" output

Points to Note​

  • Keys used as property names in JSON must always be wrapped in double quotes ("). While JavaScript objects allow single quotes ('), JSON does not.

  • Data types that are not supported by JSON (e.g., functions, undefined) cannot be converted to JSON.

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