I am not too familiar with javascript. Can someone please explain this construct to me?
[{a:"asdfas"},{a:"ghdfh",i:54},{i:76,j:578}]
What does this construct declare? I can see that this is an array that consists of 3 elements, right? And every element in this array is a class, which is declared in JSON format, isn't it? And I do not need to use any scripts to use JSON, do I?
It's simply an array composed of 3 elements. Each element is an object. The first one has the a key with associated 'asdfas' value. The second one i key with 54 value etc etc
it could be built in this way :
var arr = []; //[] <= array
var first = {}; // {} <= object
first.a = "asdfas"; // object.key = value, same by doing var first = {a:"asdfas"}
arr.push(first); //pushing an object inside the array
//arr status: [{a:"asdfas"}]
var second = {};
second.a = "ghdfh";
second.i = 54;
arr.push(second);
//arr status: [{a:"asdfas"},{a:"ghdfh",i:54}]
var third = {};
third.i = 76;
third.j = 578;
arr.push(third);
//arr status: [{a:"asdfas"},{a:"ghdfh",i:54},{i:76,j:578}]
alert(arr[2].j) //third element of the array => object => key j => alerts j value 578
This declares an array of 3 objects. The first object of this array contains one string property a = "asdfas". The second object in the array contains two properties a = "ghdfh" and i = 54. And the last object contains two numeric properties a = 76 and j = 578. So this represents a javascript object and you don't need to declare any scripts to use it:
var array = [ { a: "asdfas" },
{ a: "ghdfh", i: 54 },
{ i: 76, j: 578 }
];
alert(array[1].i); // prints the i property of the second item in the array: 54
It is an array of 3 objects.
The brackets [] indicate an array.
Each item within the array is an object, as indicated by the curly braces {}. You can think of each of these like a hash table, where a : "asdfas" means that you can reference a to look up the string value. For example:
var data = {a:"asdfas"};
alert( data.a ); // Echos "asdfas"
Regarding your question:
And I do not need to use any scripts to use JSON, do I?
No, JSON is just JavaScript Object Notation, so it is just JavaScript code. However, you will need/want to use a 3rd party library (such as json2.js) if you need to encode a JavaScript data structure as JSON or if you need to decode JSON from a string.
That is an array of object literals. You do not need any scripts or special libraries to use JSON objects within a script, but depending on your implementation, you may need to use a script to use JSON within AJAX requests. For more info, see: http://www.json.org/
EDIT: corrected per discussion in comments.
