JavaScript JSON Objects
JSON stands for JavaScript Object Notation. JSON is an open standard
lightweight format for data interchange. JSON is a format for storing and
transporting data consisting of comma-separated attribute-value pairs and array
data types. JSON is commonly used to send the information from a server to a
web page. JSON is self-describing, human-readable and easy to understand object
representation. All the programming languages can be used for reading and
generating JSON data.
JSON and JavaScript
The JSON format is syntactically similar to the code for
writing JavaScript objects. JavaScript program can be converted to JSON data
into native JavaScript objects.
JSON Syntax
- Data is represented in key-value pairs
- Data is kept by comma-separated
- Curly braces are used to hold objects
- Arrays are represented by Square brackets
A key-value pair consists of a field name (in double quotes), followed by a colon, followed by a value:
“color”:” red”
The main difference between the normal JavaScript Object and
the JSON Object is that JSON names must
be enclosed within double-quotes. We write a JavaScript Object as
employee_obj={eid:117,ename:"Harry",edept:"CSE"};
but a JSON Object is written as
employee_obj={“eid”:117,”ename”:"Harry",”edept”:"CSE"};
JSON Arrays
JSON arrays are created using square brackets and items
separated by commas, like in JavaScript:
"cars":[
{"brand":"Toyota",
"Modal":"Innova"},
{"brand":"Suzuki",
"Modal":"Dzire"},
{"KIA":"Suzuki",
"Modal":"Seltos"}
]
Converting a JSON Text to a JavaScript Object
We can take a JSON object as a String type to demonstrate the
conversion of JSON to JavaScript Object. For example
var car='{"cars":['+
'{"brand":"Toyota", "Modal":"Innova"},'+
'{"brand":"Suzuki",
"Modal":"Dzire"},'+
'{"brand":"KIA",
"Modal":"Seltos"}]}';
To convert this JSON String into JavaScript Object, We can use the JavaScript built-in
function JSON.parse(),
var car_object = JSON.parse(car);
This object can be used as a normal JavaScript object in a web
document.
Example
t<script>
var cars='{"car":['+
'{"brand":"Toyota",
"Modal":"Innova"},'+
'{"brand":"Suzuki",
"Modal":"Dzire"},'+
'{"brand":"KIA",
"Modal":"Seltos"}]}';
var car_js=JSON.parse(cars);
document.write(car_js.car[0].brand);
</script>
Output:
Toyota
