function update(){
    $.getJSON("/main/ajax_select_route",{from: $("select#from").val(), ajax: 'true'}, function(j){
      var options = '';
      for (var i = 0; i < j.length; i++) {
        options += "<option value='" + j[i].optionValue + "'>" + j[i].optionDisplay + "</option>";
      }
      $("select#to").html(options);
    })
  }

$(document).ready(function(){
	
  $("select#from").change(update);
  $("select#from").val("");
	$("input#show").click(function(event) {
		if ($("select#to").val() != 0)
	  	window.location = $("select#to").val();
	});
	update();
})