Struggling to understand .each() looping

Struggling to understand .each() looping

//CAPTURE THE 'MIDDLE' NUMBER FROM .attr("iid") INTO AN ARRAY.  So get "33803' from the .attr("iid) into an array using .each and the object $(this).  I guess i'm still missing something regarding this jquery 'looping' business.  if someone could please get me past this hump I'd appreciate it.    thanks  -dave

<table>
    <TR class=ms-itmhover id="wtf" iid="1112,33803,0" setEdgeBorder="true">wtw</TR>
    <TR class=ms-itmhover id="wtf" iid="1112,34443,0" setEdgeBorder="true">xxx</TR>
    <TR class=ms-itmhover id="wtf" iid="1112,31113,0" setEdgeBorder="true">yyy</TR>
</table>



$(document).ready(function () {
    
    var arr1 = []
    var xiid = $("TR").attr("iid");
    $(xiid).each(function() {
         var xval = $(this).replace(/^\d{4},/,""); //DELETES PREFIX
             xval = $(this).replace(/\,\d{1}$/, "");//DELETES SUFFIX
             arr1.push(xval);
             alert(arr1);
        
    }); //END EACH

}); //END READY