Animate only once
<p>I use jQuery .animate() to move an item once, but it seems to be moving in increments of 100px multiple times. Is it because of mouseover over?</p>

<pre><code>var ww = $(window).width();

$(document).on('mouseover', '#myTarget', function () {
     var dp = $(this).offset().left;

     if ((ww - dp) &lt; 150) {
         $('.myDiv.active').animate({left:'-=100px'},500);
     }
}); 
</code></pre>