`this` in callback functions
<p>I used to use</p>

<pre><code>MyClass.prototype.myMethod1 = function(value) {
    this._current = this.getValue("key", function(value2){
        return value2;
    });
};
</code></pre>

<p>How do I access the value of this within the callback function like below?</p>

<pre><code>MyClass.prototype.myMethod1 = function(value) {
   this.getValue("key", function(value2){
       //ooopss! this is not the same here!    
       this._current = value2;
   });
};
</code></pre>
