In the following javascript code, why variable that is not accessible to func function? : <pre><code>var func=function(){console.log(that)}
var obj = {
    foo(){
        var that=this;
        var a=func;
        a();
    }
}   

obj.foo();
</code></pre>

<p><strong>Result :</strong> </p>

<p><em>Uncaught ReferenceError: that is not defined</em></p>
