JSON

JSON

 * Javascript object notation.

* JSON is a syntax for storing and exchanging data.

* JSON is text,written with javascript object notation 

 1.what is JSON?

• Json  stands for javascript object notation.
• JSON is a lightweight data-interchange format.
• JSON is ¨self-describing¨ and easy to understad.
• JSON is language independent.

 1.Why use  JSON?

• since the jSON format is text only.it use easily be sent to and form a server.and used as a data format  by any programming language.

• Javascript has a built in function to convert a string. written in JSON format. into native javascript.       

JSON.parse()

• So if you receive data from a server in JSON format. you can use it like any other  javascript  object.

Exchanging Data

• when exchanging data between a browser and a server,the data can only be text.
•  JSON is text,andwe can convert any javascript object into JSON, and  send JSON to the server .

• we can also convert any JSON received  from the server into javascript objects.

Sending Data 

• If you have data stored in a javascript  object.you can convert the object into JSON, and send it to a server.

Examble:
  

 

Receiving Data

• If you have receive data in JSON format.you can convert it into a javascript object.

Examble:

 

  Storing Data

• When storing data, the data has to be a certain format , and regardless of where you choose to store it text is always one of the legal formats. 

   

  Examble:

  

   JSON Syntax

  * The JSON syntax is a subset of the javascript syntax. 
  * JSON Syntax Rules 
        1.Data is in name/value pairs.
        2.Data is separated by commas.
        3.Curly braces hold objects.
        4.Square brackets hold arays
  * JSON ---{"name":"mayoori"} 
  * Javascript ---{name:"mayoori"} 
  JSON datatypes
  1.String
          {"name":"mayoori"}
  2.Number 
          {"age":20}
  
  3.Booleans
          {"sale":true}
  
  4.Objects
         { "employee"{"name":"mayoori","age":20,"city":"jaffna"}
         }
  
   
  5.Arrays
         {"employee":
  ["thanu","siva","jano"]
          }
  
  6.Null 
        {"middlename":null}  
  

   

   we can access a javscript obect like this

  * var person ={"name":"mayoorika","age":"20"};

1.person.name;
2.person["name"];
3.person.name="thanusha";
4.person.["name"]="thanu";

  

Objects

• JSON objects are surrounded by curly breces{}.
• JSON object are written in key/value pairs.
• Key must be strings,and values must be a valid json data type(string,number,boolean,object,null).

assessing object valus 
    
1. (.) Notation.
       myobj={"name":"mayoo","age":20};
       x=myobj.name; 

2.([]) bracket notation.
        myobj={"name":"mayoo","age":20};
        x=myobj["name"] ;
       

3.Looping an object.

      myobj={"name":"mayoo","age":20};

      for(x in myobj)

     {document.getElementById("demo").innerHTML   +=x;}