javascript class problem
<p>Examine this code</p>

<pre><code>    var _class=function()
    {
        this.Test=100;
        this.Callback=function(msg)
        {
            alert(msg+"\r\n"+this.Test);
        }
    }

    function run(call)
    {
        call("Hello world");
    }

    var obj=new _class();
    run(obj.Callback);
</code></pre>

<p>I got the result :</p>

<pre><code>    [Alert]
    Hello world
    undefined
</code></pre>

<p>but when i call 
      obj.Callback("Hello world")</p>

<p>i got expected</p>

<pre><code>    [Alert]
    Hello world
    100
</code></pre>

<p>why ?</p>

<p>thank for help</p>
