What Is JSON?

kc@example.com (kc kim) — Mon, 25 Dec 2017 19:06:24 +0900

JSON Overview

JSON, or JavaScript Object Notation, is a lightweight text format for data interchange. It is easy for people to read and write and is supported by many programming languages.

JSON was popularized by Douglas Crockford.
JSON files commonly use the .json extension.
The Internet media type is application/json.
JSON text exchanged between systems is encoded in UTF-8.

Common Uses

Sending structured data between web clients and servers
Building web APIs
Storing configuration and application data
Exchanging data between programs written in different languages

Syntax

JSON values include objects, arrays, strings, numbers, booleans, and null.

Type	Description
Number	integer or decimal number, optionally with an exponent
String	Unicode characters enclosed in double quotation marks
Boolean	`true` or `false`
Array	ordered list of values
Object	collection of name-value pairs
`null`	empty value

Numbers

Numbers are written without quotation marks.

{ "marks": 97 }

JSON does not support hexadecimal notation, NaN, or infinity.

Strings

Strings use double quotation marks.

{ "name": "Amit" }

Common escape sequences include \", \\, \/, \b, \f, \n, \r, \t, and \uFFFF.

Booleans and null

{
  "distinction": true,
  "deletedAt": null
}

Arrays

Arrays are ordered lists enclosed in brackets.

{
  "books": [
    { "language": "Java", "edition": "second" },
    { "language": "C++", "edition": "fifth" },
    { "language": "C", "edition": "third" }
  ]
}

Objects

Objects contain unique string keys and values.

{
  "id": "011A",
  "language": "JAVA",
  "price": 500
}

Using JSON in JavaScript

A JSON-shaped JavaScript object can be created with an object literal.

var book = {
  "name": "JSON Guide",
  "price": 500
};

document.write(book.name);

Strict JSON is a data format rather than executable JavaScript. Use JSON.parse() to read JSON text and JSON.stringify() to serialize a JavaScript value.

var text = '{"name":"JSON Guide","price":500}';
var book = JSON.parse(text);
var serialized = JSON.stringify(book);

Example

{
  "book": [
    {
      "id": "01",
      "language": "Java",
      "edition": "third",
      "author": "Herbert Schildt"
    },
    {
      "id": "07",
      "language": "C++",
      "edition": "second",
      "author": "E. Balagurusamy"
    }
  ]
}

devkuma – JSON