<select id="selectstation">
</select>

$(function () {
 $.post(url, { "action": "station" }, function (data) {
                var dataObj = eval(data);
                var element = document.getElementById("selectstation");
                element.setAttribute("onchange", "DataStatistics()");
                           
                for (var i = 0; i < dataObj.total; i++) {
                    var para = document.createElement("option");
                    para.setAttribute("value", dataObj.rows[i]["JSON_station_code"]);
                    if (i == 0)
                    {
                        para.selected = "selected";   
                    }
                    para.innerHTML = dataObj.rows[i]["JSON_station_name"];
                    var element = document.getElementById("selectstation");
                    element.appendChild(para);
                }
            }, 'json');
DataStatistics();
 });     
    
function DataStatistics()
        {
            var phase1 = document.getElementById("selectstation");
            var e = $("#selectstation ").val();
            e = $("#selectstation").children(0).val();
            e = $('#selectstation option:selected').val();//选中的值
            e= phase1.value;
            e= phase1.innerHTML;

        }