Objects in Javascript - Objekt i Javaskript

Modified on 2014/03/18 15:24 by Jovall — Categorized as: Uncategorized

Everything is an object - Allt är objekt

In Javascript everything is an object; apart from the following basic datatypes: strings, numbers, booleans, null and undefined. Objects can be seen as belonging to specific categories. They are:

native objects - objects provided by Javascript
host objects - objects provided by the hosting context, e.g. a web browser
user-defined objects - objects that are created in code by the user (programmer)

Objects - Objekt

An object is a collection of properties. Objects are handled as references, not as values. Each object also contains a set of object attributes:

prototype - referens to an object that is inherited, who's properties are also part of this object
class - a string that identifies an objects "identity"
extensible - a flag indicating whether one can att properties to this object

Creating an object

Objects are created by one of three ways:

object literal - a comma-separated list of propertyname-and-value-pairs separated by colon : var theName = { x:1, "main title":"An awesome title" }
using the new operator - calling a constructor function with new : var theName = new NewObject()
using the create function - calling the create-function using the prototype and properties for the new object : var theName = Object.create({x:1}, {y:2, z:3})