What is JSON?

JSON stands for JavaScript Object Notation
JSON is a lightweight data interchange format
JSON is language independent
JSON is “self-describing” and easy to understand

Ex:

{
 "type": "laptop",
 "brand": "Sony",
 "operating system": "Windows 7",
 "graphic card": "NVIDIA"
}

{

"type": "laptop",

"brand": "Sony",

"operating system": "Windows 7",

"graphic card": "NVIDIA"

}

The JSON format is syntactically identical to the code for creating JavaScript objects:

keys: type, brand, operating system, graphic card
values: _laptop, Sony, Windows 7, NVIDIA

Because of this similarity, a JavaScript program can easily convert JSON data into native JavaScript objects.

JSON Syntax Rules

Data is in name/value pairs
Data is separated by commas
Curly braces hold objects
Square brackets hold arrays

JSON Data – A Name and a Value

JSON data is written as name/value pairs, just like JavaScript object properties.

A name/value pair consists of a field name (in double quotes), followed by a colon, followed by a value:

"firstName":"John"

1	"firstName":"John"

JSON Objects

JSON objects are written inside curly braces.

Just like in JavaScript, objects can contain multiple name/value pairs:

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

1	{"firstName":"John", "lastName":"Doe"}

JSON Arrays

JSON arrays are written inside square brackets.

Just like in JavaScript, an array can contain objects:

"employees":[
  {"firstName":"John", "lastName":"Doe"},
  {"firstName":"Anna", "lastName":"Smith"},
  {"firstName":"Peter", "lastName":"Jones"}
]

"employees":[

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

{"firstName":"Anna", "lastName":"Smith"},

{"firstName":"Peter", "lastName":"Jones"}

]

In the example above, the object “employees” is an array. It contains three objects.

Each object is a record of a person (with a first name and a last name).

JSON – JavaScript

JavaScript provides us with two functions: JSON.stringify and JSON.parse:

JSON.stringify is used to convert a JavaScript Object into a JSON string.
JSON.parse is used to convert a string representing JSON into a JavaScript Object.

Ex:

var string = JSON.stringify({name: "X", born: 1990});
console.log(string);
// => {"name":"X","born":1990}

var obj = JSON.parse(string);
console.log(obj.name);
// => X
console.log(obj.born);
// => 1990

var string = JSON.stringify({name: "X", born: 1990});

console.log(string);

// => {"name":"X","born":1990}

var obj = JSON.parse(string);

console.log(obj.name);

// => X

console.log(obj.born);

// => 1990

That means if you want to edit JSON, you can convert it to Object to modify attributes and values. Then convert that JavaScript Object back into JSON.