JavaScript OOP error
<p>Hello this is my first attempt at trying to write a JavaScript application so I'm new to writing OOP code using it. </p>

<p>The following code runs without any errors in the console:</p>

<pre><code>// Main file for the application
$(document).ready( function()
{
    var app = new application;
    setInterval( app.run, 50 );

});

function application()
{
   var canvas = Raphael(10,0,400,400);
   this.molecule = new molecule( new Vec2(50,50),new Vec2(1,0),canvas );
   this.molecule.update(10);

   this.run = function()
    {

    }
}
</code></pre>

<p>However, this piece of code does not work:</p>

<pre><code>// Main file for the application
$(document).ready( function()
{
    var app = new application;
    setInterval( app.run, 50 );

});

function application()
{
   var canvas = Raphael(10,0,400,400);
   this.molecule = new molecule( new Vec2(50,50),new Vec2(1,0),canvas );

   this.run = function()
    {
        this.molecule.update(10);
    }
}
</code></pre>

<p>It gives the following error in the console:</p>

<pre><code>Uncaught TypeError: Object function molecule( pos,vel,canvas )
    {
        this.radius = 5;
        this.color = "red";

        this.canvas = canvas;

        this.pos = pos;
        this.vel = vel;

        this.circle = canvas.circle( this.pos.x,this.pos.y,this.radius );

        this.circle.attr("fill", this.color );


    } has no method 'update' 
</code></pre>

<p>Here is the source file containing the molecule object.</p>

<pre><code>    // This 'class' handles a molecule, including movement and drawing.

    function molecule( pos,vel,canvas )
    {
        this.radius = 5;
        this.color = "red";

        this.canvas = canvas;

        this.pos = pos;
        this.vel = vel;

        this.circle = canvas.circle( this.pos.x,this.pos.y,this.radius );

        this.circle.attr("fill", this.color );


    }

 // Updates the molecule
    molecule.prototype.update = function( deltaTime )
    {
        this.pos += this.vel * deltaTime;
        this.setPosition(this.pos);
    }

    // Accepts a Vec2
    molecule.prototype.setPosition = function( pos )
    {
        this.circle.translate( pos.x-this.pos.x, pos.y-this.pos.y );
    }    
</code></pre>

<p>I'm sorry for the large amount of code I've posted, but I'm stumped why the first piece of code works while the second won't. Could anybody shed some light on it for me? Thanks a lot. </p>
