Objects
An object is just a special kind of data, with Properties and Methods.
JavaScript allows you to define your own objects.
// To declare an object
var person={ firstname : "John", lastname : "Smith", age: 25};
// Use spaces and line breaks to make your definition clearer
var person={
firstname : "John",
lastname : "Smith",
age : 25
};
// You can access object properties in two way
var age = person.age;
var age = person["age"];
The object (person) in the example above has 3 properties: firstname, lastname, and age.
Properties
Properties are the values associated with an object.
The syntax for accessing the property of an object is:
objectName.propertyName
This example uses the length property of the String object to find the length of a string:
var message = "Hello World!";
var x = message.length;
The value of x, after execution of the code above will be 12.
Methods
Methods are the actions that can be performed on objects.
You can call a method with the following syntax:
objectName.methodName()
This example uses the toUpperCase() method of the String object, to convert a text to uppercase:
var message="Hello world!";
var x = message.toUpperCase();
The value of x, after execution of the code above will be “HELLO WORLD!”.