如何简化这个Javascript函数？

我正在尝试扩展这个但是在创建JS函数时我有点绿.我设法自己走了这么远,但唉......

当跨度获得任何值(在本例中为城市名称)时,我希望选择框自动匹配它.而且我想通过摆脱所有这些来扩展它,如果是的话.

$(document).ready(function() {
  $('select#field1 option').removeAttr('selected');
  var whereEvent = $('span#field2').html();
  if (whereEvent == 'New York') {
    $('select#field1 option[value=New York]').attr('selected', 'true');
  } else if (whereEvent == 'Los Angeles') {
    $('select#field1 option[value=Los Angeles]').attr('selected', 'true');
  } else if (whereEvent == 'Tokyo') {
    $('select#field1 option[value=Tokyo]').attr('selected', 'true');
  } else if (whereEvent == 'London') {
    $('select#field1 option[value=London]').attr('selected', 'true');
  } else if (whereEvent == 'Sydney') {
    $('select#field1 option[value=Sydney]').attr('selected', 'true');
  } else if (whereEvent == 'Paris') {
    $('select#field1 option[value=Paris]').attr('selected', 'true');
  }
});

有人可以帮帮我吗？我保证我会感激你的帮助.谢谢.

这是一个选项:

    $(document).ready(function() {
      $('select#field1 option').removeAttr('selected');
      var whereEvent = $('span#field2').html();
      var filter = 'select#field1 option[value=' + whereEvent + ']';
      $(filter).attr('selected', 'true');
   }

或者你可以这样做:

    $(document).ready(function() {
      var filter = $('span#field2').html();
      $('select#field1 option').each(function(){
           this.selected = (this.value == filter);
      });
   }