<script type="text/javascript">
jQuery(document).ready(function($){
    var $div = $('div');
    var $widthSpecified = $div.filter(function(){
        return this.style.width != ''; null;
    });
    var $widthUnspecified = $div.not($widthSpecified);
    alert($widthSpecified.length);
    alert($widthUnspecified.length);
});
</script>
<div style="width: 1px;"></div>
<div></div>
<div style="width: 2px;"></div>