JavaScript: Basic Extensions (1)--json

JavaScript: Extending Knowledge (1)--json Understanding:

The most important thing about JSON is to understand that it is a data format, not a programming language . Although it has the same syntactic form, JSON does not belong to JavaScript. Also, JSON is not only used by JavaScript, after all, JSON is just a data format. Many programming languages have parsers and serializers for JSON.

• The file type of the JSON file is ". JSON"
• The MIME type of JSON text is "Application/json"

Syntax:JSON fetch value

• Number (integer or floating point)
• String (in double quotes)
• Logical value (TRUE or FALSE)
• Array (in brackets)
• Object (in curly braces)
• Null

{"Age": "Flag":true"Runoob":null }

Object

Description

The 1.JSON object is written in {}.

2. An object can contain multiple key/value (key/value) pairs.

3.key must be a string and value must be a valid JSON data type.

Use colons (:) split in 4.key and value. Each key/value pair uses commas (,) to split.

Object notation:

/* JSON Object Notation */ {  "name":"MS",  "age": +,        "id": 10010}

Object array:

/* JSON Array */ [  {"title": "A", "num": Ten},  {"title": "B", "num": +},  {"title": "C", "num": 30 }]

To access the object value:

/* use the. Access Object Value */ var  = {"Name": "Runoob", "Alexa": 10000, "site":null= myobj.name; /* accessing object values using [] */ var  = MYOBJ = {"Name": "Runoob", "Alexa": 10000, "site":null
x = myobj["name"];

Using loops to traverse an object

var myObj = {"Name": "Runoob", "Alexa": 10000, "site":null  };  for inch MYOBJ) {    document.getElementById ("Demo"). InnerHTML + = Myobj[x] + "<br>";}

Nested JSON objects

One JSON object nesting another JSON object

MYOBJ = {    "name": "Runoob",    "Alexa": 10000,    "Sites": {         "Site1": "www.runoob.com",        "site2": "m.runoob.com",        "site3": "C.runoob.com"     }}

To access nested JSON objects

x = myObj.sites.site1; // or x = myobj.sites["Site1"];

modifying values

myObj.sites.site1 = "www.google.com"; myobj.sites["site1"] = "www.google.com";

Delete Object Properties

Delete myObj.sites.site1; Delete myobj.sites["site1"]

parsing and serialization parsing

Description

• JSON is typically used to exchange data with the server.
• is typically a string when receiving server data.
• We can use the Json.parse () method to convert data to JavaScript objects.

　　

Receiving JSON data from the server (http://www.runoob.com/json/json-parse.html)

Use AJAX to request JSON data from the server and parse it into a JavaScript object.

var New  function() {    if (this this. Status = =) {         = Json.parse (this. responsetext);        document.getElementById ("Demo"). InnerHTML = myobj.name;    }}; Xmlhttp.open (true); Xmlhttp.send ();

Serialization of

Description

• JSON is typically used to exchange data with the server.
• is typically a string when sending data to the server.
• We can use the Json.stringify () method to convert a JavaScript object to a string.

• Json.stringify (value[, replacer[, space])

　　

JavaScript: Basic Extensions (1)--json