Javascript Autocomplete email's domain using jQuery UI -

i need help, stuck trying make following case scenario work: have email input field, type: foo@y - should pop autocomplete box, offering yahoo.com (for example). if take suggestion, end value should become: foo@yahoo.com

i have wrote code (modified off jquery ui sample):

         $( "#tags" )             // don't navigate away field on tab when selecting item             .bind( "keydown", function( event ) {                 if ( event.keycode === $.ui.keycode.tab &&                         $( ).data( "autocomplete" ).menu.active ) {                     event.preventdefault();                 }             })             .autocomplete({                 minlength: 3,                 source: function( request, response ) {                             var mail_regex = /^([\w.]+)@([\w.]+)$/;                             var match = mail_regex.exec(request.term);                             if (match)                                 var matcher = new regexp( "^" + match[2], "i" );                             response( $.grep( availabletags, function( item ){                                 return matcher.test( item );                             }) );                  },                 focus: function() {                     // prevent value inserted on focus                     return false;                 },                 select: function( event, ui ) {                     var terms = split( this.value );                     // remove current input                     terms.pop();                     // add selected item                     terms.push( ui.item.value );                     // add placeholder comma-and-space @ end                     terms.push( "" );                     this.value = terms.join( ", " );                     return false;                 }             }); 

full working interactive sample: http://jsfiddle.net/rrf2s/3/

however, replaces foo@ yahoo.com - can not life of me figure out how override behaviour...

any javascript/jquery masters - please! how accomplish goal? tried doing: return match[1]+matcher.test( item ), not work.

here complete code:

$(function() {     var availabletags = [         "yahoo.com",         "gmail.com"     ];     function extractlast( val ) {         if (val.indexof("@")!=-1){             var tmp=val.split("@");             console.log(tmp[tmp.length-1]);             return tmp[tmp.length-1];         }         console.log("returning empty");         return "";     }      $( "#tags" )         // don't navigate away field on tab when selecting item         .bind( "keydown", function( event ) {             if ( event.keycode === $.ui.keycode.tab &&                     $( ).data( "autocomplete" ).menu.active ) {                 event.preventdefault();             }         })         .autocomplete({             minlength: 1,             source: function( request, response ) {                         var mail = extractlast(request.term);                         if(mail.length<1){return;}                         var matcher = new regexp( "^" + mail, "i" );                         response( $.grep( availabletags, function( item ){                             return matcher.test( item );                         }));              },             focus: function() {                 // prevent value inserted on focus                 return false;             },             select: function( event, ui ) {                 var terms = this.value.split(", ");                 // remove current input                 var ml=terms[terms.length-1].split("@")[0];                 terms.pop();                 // add selected item                 terms.push( ml+"@"+ui.item.value );                 // add placeholder comma-and-space @ end                 terms.push( "" );                 this.value = terms.join( ", " );                 return false;             }         }); });