JSON schema

- Describes your existing data format
- Defines the structure of a JSON message
- Clear, human- and machine-readable documentation
- Complete structural validation, useful for automated testing
- Complete structural validation, validating JSON message
- Can be used to validate API request and response

Object

Array

var obj = { name: "John", age: 30, city: "New York" };

// Converts object into JSON string
var myJSON = JSON.stringify(obj);

// Puts the string into element with id: demo
document.getElementById("demo").innerHTML = myJSON;

JSON.parse()

let txt = '{"name":"John", "age":30, "city":"New York"}'

// Converts JSON string into a JavaScript object.
let obj = JSON.parse(txt);

// Puts the data into "p" element with id: demo
document.getElementById("demo").innerHTML = obj.name + ", " + obj.age;

$arr = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5);

// Returns the JSON representation of a value (pretty printed)
echo json_encode($arr, JSON_PRETTY_PRINT);

{
    "a": 1,
    "b": 2,
    "c": 3,
    "d": 4,
    "e": 5
}

class Emp {
    public $name = "";
    public $hobbies  = [];
    public $birthdate = "";
}

$e = new Emp();
$e->name = "sachin";
$e->hobbies  = ["sport", "reading"];
$e->birthdate = date('Y-m-d', strtotime('2015-11-18'));

echo json_encode($e);

{"name":"sachin","hobbies":["sport","reading"],"birthdate":"2015-11-18"}

$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';

// Decoding into an object
var_dump(json_decode($json));

// Decoding into an array
var_dump(json_decode($json, true));

object(stdClass)#1 (5) {
  ["a"]=> int(1)
  ["b"]=> int(2)
  ["c"]=> int(3)
  ["d"]=> int(4)
  ["e"]=> int(5)
}
array(5) {
  ["a"]=> int(1)
  ["b"]=> int(2)
  ["c"]=> int(3)
  ["d"]=> int(4)
  ["e"]=> int(5)
}

- Both JSON and XML are "self describing" (human readable)
- Both JSON and XML are hierarchical (values within values)
- Both JSON and XML are language independent
- Both JSON and XML can be parsed and used by lots of programming languages
- Both JSON and XML can be fetched with an XMLHttpRequest

+ JSON doesn't use end tag
+ JSON is shorter
+ JSON is quicker to read and write
+ JSON can use arrays
+ Better Performance
+ JSON can be parsed easily
+ JSON object has a type
+ All major JavaScript frameworks support JSON
+ Supported by all major JavaScript frameworks
+ Supported by most backend technologies
+ JSON is recognized natively by JavaScript (as object)
- JSON doesn't support comments
- JSON can not use attributes
- JSON offers poor extensibility as no namespace support
- Supports limited data types

{
   "company": Volkswagen,
   "name": "Vento",
   "price": 800000
}

<car>
   <company>Volkswagen</company>
   <name>Vento</name>
   <price>800000</price>
</car>

{
   "employees":[
      {"firstName":"John", "lastName":"Doe"},
      {"firstName":"Anna", "lastName":"Smith"},
      {"firstName":"Peter", "lastName":"Jones"}
   ]
}

<employees>
  <employee>
    <firstName>John</firstName> <lastName>Doe</lastName>
  </employee>
  <employee>
    <firstName>Anna</firstName> <lastName>Smith</lastName>
  </employee>
  <employee>
    <firstName>Peter</firstName> <lastName>Jones</lastName>
  </employee>
</employees>

- a function
- a date
- a symbol
- undefined

key/value

:

key/value

comma

key

strings

{}

{

}

{
   "id": "011A",
   "language": "JAVA",
   "price": 500,
}