What is the differnce between "!" and "!!"
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/784929/what-is-the-not-not-operator-in-javascript">What is the !! (not not) operator in JavaScript?</a>  </p>
</blockquote>



<p>I removed !! and put in ! and it broke my code...googled javascript !! and got nothing not even !.  I believe ! is the not operator but what is !!...realy realy not.</p>

<pre><code>function domPaneFlip()
{
    var button_element = document.getElementById( 'bookmark_flip_button' ),
        bookmark_list = document.getElementsByName( 'bookmark_link' ),
        bookmark_element,
        iterator = 0;
    if( domPaneFlip.p1 === 'Done' )
    {
        domPaneFlip.p1 = 'Delete';
        domPaneFlip.p2 = 'bookmark';
        while( !!( bookmark_element = bookmark_list[ iterator++ ] ) )
        {
            bookmark_element.removeEventListener( "click", MBookmarkDelete );
            bookmark_element.className = domPaneFlip.p2;
        }
    }
    else
    { 
        domPaneFlip.p1 = 'Done';
        domPaneFlip.p2 = 'bookmark_delete';
        while( !!( bookmark_element = bookmark_list[iterator++] ) )
        {
            bookmark_element.addEventListener( "click", MBookmarkDelete );
            bookmark_element.className = domPaneFlip.p2;
        }
    }
    button_element.innerHTML = domPaneFlip.p1;
}
</code></pre>
