What is JSON
JSON stands for JavaScript Object Notation. It is an open standard data interchange and file format. It was first invented by Douglas Crockford. It is a generic, lightweight, self-describing, human readable, language independent format that uses for storing and transporting data. Since it stores data in object pattern, it easy to read and write. Although it is language independent, actually it was derived from JavaScript language. It is supported by many development environments. JSON file is basically a text file with extension .json.
Mostly it uses when web applications communicate with a server. Common use is read data from server and display in web page. We can send JSON to the server and convert JSON received from server into JavaScript objects. JSON can include basic data types as Number, String, Boolean, Array, Object, Null values etc. JSON objects can not have data types like function, date, undefined etc.
This example defines an object called “employee”
{
“employees”:[
{“firstName”:”John”, “lastName”:”Doe”},
{“firstName”:”Anna”, “lastName”:”Smith”},
{“firstName”:”Peter”, “lastName”:”Jones”}
]
}
In this format data is stored in key value pairs. Key value pair consists field name and value in double quotes. Key and value separated by colon. Data is separated by commas. Objects are written in Curly braces. Square brackets hold arrays. Every misplaced colon or comma can produce errors.
This example defines an object called “menu” and as we mentioned before “menuItem” is a example for array data type
{“menu”: {
“id”: “file”,
“value”: “File”,
“popup”: {
“menuitem”: [
{“value”: “New”, “onclick”: “CreateDoc()”},
{“value”: “Open”, “onclick”: “OpenDoc()”},
{“value”: “Save”, “onclick”: “SaveDoc()”}
]
}
}}
This helps convert JSON data into JavaScript objects. JavaScript use JSON.parse() in built method to convert string into JavaScript object
var obj = JSON.parse(text);
we use JSON.stringfy() method to convert JavaScript object into a JSON
var myObj = {name: “John”, age: 31, city: “New York”};
var myJSON = JSON.stringify(myObj);
window.location = “demo_json.php?x=” + myJSON;
there can be nested JSON object as well
myObj = {
“name”:”John”,
“age”:30,
“cars”: {
“car1”:”Ford”,
“car2”:”BMW”,
“car3”:”Fiat”
}
}
