Javascript : is given function empty?
<p>Let's have a function call</p>

<pre><code>function doSomethingAndInvokeCallback(callback){
    // do something
    callback();
}
</code></pre>

<p>I can check if given argument is function <code>if(typeof callback == 'function')</code>  </p>

<p>How can I discover, if given callback function is function and isn't empty?</p>

<p>like</p>

<pre><code>doSomethingAndInvokeCallback(function(){
    //nothing here
})
</code></pre>
