AJAX - The Complete Reference

560 Part IV: Appendixes

Object Creation

Objects are created using the new operator in conjunction with a special constructor function.

[var] instance = new Constructor(arguments);

For example, here we create a new Date object that is built-in to ECMAScript:

var today = new Date();

Constructor functions are by convention named in uppercase and can be user defined.

This shows an example of creating a simple object Dog with one property and method.

function Dog(name)

{

this.name = name;

this.bark = function () { alert("woof woof!"); };

}

var angus = new Dog("Angus Dunedin Powell");

alert(angus.name);

angus.bark();

Besides constructing objects with new, it is also possible that Object literals may be

used with the following syntax:

{ [ prop1: val1 [, prop2: val2, ...]] }

For example:

var myDog = {

name : "Angus"

city : "San Diego",

state : "CA" ,

friendly : true,

greeting : function() { alert("Ruff ruff!"); }

}

Object literals are quite important in JavaScript today as they are being co-opted to

create a namespace-like wrapper around various user-defined variables and functions. For

example, given:

var gServiceId = 5551212;

function send() { }

function receive() { }

you would wrap the values and functions within an object literal like so:

var fakeNS = {

gServiceId : 5551212,

send: function () { },

receive: function () { }

}

and avoid polluting the shared global namespace with many identifiers.