jQuery(function($) {

  var testValues = [

    {test: "string.name+org.com", expect: "com"},

    {test: "last.fm", expect: "fm"},

    {test: "stuff;here", expect: "here"},

    {test: "more_stuff", expect: "stuff"},

    {test: "nonefound", expect: "nonefound"}

  ];

​

  $.each(testValues, function(i, entry) {

    test(entry.test, entry.expect);

  });

  function test(value, expect) {

    var match = /([^.;+_]+)$/.exec(value),

        result = match && match[1];

    display("Test '" + value + "', result '" + result + "'",

            result === expect ? "good" : "bad");

  }

  function display(msg, className) {

    var p = $("<p>").html(msg).appendTo(document.body);

    if (className) {

      p.addClass(className);

    }

  }

});