World Wide Web

JavaScript

Tutorial — Creating New Objects

Advanced Class Design

This page is a work in progress.
(Early in its progress.)

Introduction

Following are some advanced techniques for JavaScript classes.

Static Methods

JavaScript support static methods in various ways. (JavaScript supports stand-alone functions, so you don't need static methods for that purpose.)

What it boils down to is that, since functions are first-class objects in JavaScript, all you need to do is define a function and bind it to a one-of-a-kind object.

With our Point example, you could bind some functions directly to the Point() constructor function. These functions would be available through the Point() function as an object.

For example, start with our friend the Point constructor, and add...:

function Point(x,y)
{
    this.x = (x == undefined? 0: x);
    this.y = (y == undefined? this.x: y);
    this.Reset = function () {
        this.x = 0;
        this.y = 0;
    }
    this.Move = function (x,y) {
        this.x = x;
        this.y = y;
    }
    this.toString = function () {
        return 'Point:x,y=' + this.x + ',' + this.y;
    }
}
// Create new Point function member...
Point.GetNewPoint = function ()
{
   return new Point(-1,-1);
}

Use this new static method to return new objects with a specific value:

var  o1 = new Point(21,42);
var  o2 = Point.GetNewPoint();

Print(o1);
Print(o2);

When run, the output is:

Point:x,y=21,42 
Point:x,y=-1,-1 

Advanced Technique #91455