Find the userId from a people picke

<script type="text/javascript" src="../../Javascript/jquery-1.3.2.min.js"></script>
<script type="text/javascript">
fields = init_fields();
// Find the userId from a people picker in DispForm
var userIdRaw = $(fields['client']).find('.ms-formbody a').attr('href');
var userId = userIdRaw.substring(userIdRaw.indexOf('=')+1);
// Here is the userId for the person in the people picker
alert(userId);

function init_fields(){
 var res = {};
 $("td.ms-formbody").each(function(){
   if($(this).html().indexOf('FieldInternalName="')<0) return;
   var start = $(this).html().indexOf('FieldInternalName="')+19;
   var stopp = $(this).html().indexOf('FieldType="')-7;
   var nm = $(this).html().substring(start,stopp);
   res[nm] = this.parentNode;
 });
 return res;
}
</script>