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})