JSON Quick Start Guide __json

What is JSON?

JSON(JavaScript Object notation), a syntax for storing and exchanging text information, a lightweight text data interchange format, similar to XML, but smaller, faster, and easier to parse than XML. notation
JSON is independent of a variety of programming language platforms, and almost all major programming languages have built-in support for JSON data formats. JSON syntax rules

The JSON syntax is a subset of the JavaScript Object notation syntax: Data in the form of a name/value pair representing data in comma-delimited curly braces save an array of JSON values

A JSON name value pair includes a field name (enclosed in double quotes), a colon followed by a value, such as:

"username": "Jessica"

JSON values can contain several types: numeric (integer and floating-point) strings (in double quotes) logical value (TRUE or FALSE) an array (in brackets) an object (in curly braces) a null JSON object and a JSON array

The JSON object is contained in curly braces and can contain multiple name/value pairs whose values can be arrays; The JSON array is contained in square brackets and can contain multiple objects. JSON can either begin with curly braces or begin with square brackets , and JSON objects and JSON arrays can be nested with each other, such as:

{"
    users": [
        {"username": "Jacky", age:30},
        {"username": "Jessica", age:23},
        {"username": "James", AGE:42}
    ]
}

JSON fileThe suffix of the JSON file is: ". JSON" the MIME type of the JSON file is: "Application/json" JSON parsing and serialization

The early JSON parser is basically the eval () function that uses JavaScript. Because JSON is a subset of the JavaScript syntax, the eval () function can parse and return JavaScript objects and arrays.
The ECMAScript 5 defines the behavior of parsing JSON, defining global object JSON. JSON parsing

Use json.parse () to parse the string into a JSON object or array.

Returns the JSON object
var jsonStr1 = ' {username ': ' Jessica ', ' Age ':} ';
var jsonobj = Json.parse (JSONSTR1);
Console.log (Jsonobj.username); Jessica
Console.log (jsonobj.age)//23

//return JSON array
var jsonStr2 = ' [{' username ': ' Jacky ', ' Age ': 30}, {' Username ":" Jessica "," Age ":}] ';
var Jsonarr = Json.parse (JSONSTR2);
for (Var i=0;i<jsonarr.length;i++) {
    console.log (jsonarr[i].username);//jacky Jessica
}

JSON serialization

Serializes a JSON object or array into a string using json.stringify () .

Serialized JSON object
var jsonobj = {
    "username": "Jessica",
    "Age":
};
var jsonStr1 = json.stringify (jsonobj);
Console.log (JSONSTR1); {' username ': ' Jessica ', ' age ': '

/' serialized JSON array
var jsonarr = [
    {' username ': ' Jacky ', ' Age ':},
    {' Username ":" Jessica "," Age ":}
];
var jsonStr2 = json.stringify (Jsonarr, NULL, 2);
Console.log (JSONSTR2); 
/* Output Result:
[
  {
    "username": "Jacky",
    "Age":
  },
  {
    "username": "Jessica",
    "" Age ":
  }
]
* *

* In addition, when the serialized string is longer, you can indent the string by setting the third parameter of the Json.stringify () method, which is convenient for debugging.