JSON
- Introduction
JSON:
JavaScript Object Notation.
JSON is a
syntax for storing and exchanging data.
JSON is
text, written with JavaScript object notation.
Exchanging
Data
When
exchanging data between a browser and a server, the data can only be text.
JSON is
text, and we 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.
This way we
can work with the data as JavaScript objects, with no complicated parsing and
translations.
Sending Data
If you have
data stored in a JavaScript object, you can convert the object into JSON, and
send it to a server:
Example
var
myObj = { "name":"John", "age":31,
"city":"New York" };
var
myJSON = JSON.stringify(myObj);
window.location
= "demo_json.php?x=" + myJSON;
»
You will
learn more about the JSON.stringify() function later in this tutorial.
Receiving
Data
If you
receive data in JSON format, you can convert it into a JavaScript object:
Example
var
myJSON = '{ "name":"John", "age":31,
"city":"New York" }';
var
myObj = JSON.parse(myJSON);
document.getElementById("demo").innerHTML
= myObj.name;
»
You will
learn more about the JSON.parse() function later in this tutorial.
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.
JSON makes
it possible to store JavaScript objects as text.
Example
Storing data
in local storage
//Storing
data:
myObj
= { "name":"John", "age":31,
"city":"New York" };
myJSON
= JSON.stringify(myObj);
localStorage.setItem("testJSON",
myJSON);
//Retrieving
data:
text
= localStorage.getItem("testJSON");
obj
= JSON.parse(text);
document.getElementById("demo").innerHTML
= obj.name;
»
What is
JSON?
JSON stands
for JavaScript Object Notation
JSON is a
lightweight data-interchange format
JSON is
"self-describing" and easy to understand
JSON is
language independent *
*
JSON uses
JavaScript syntax, but the JSON format is text only.
Text can be
read and used as a data format by any programming language.
The JSON
format was originally specified by Douglas Crockford.
Why use
JSON?
Since the
JSON format is text only, it can easily be sent to and from 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 objects:
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