年月日选择器

html部分：

<select class="sel_year" rel="2000"> </select> 年
<select class="sel_month" rel="2"> </select> 月
<select class="sel_day" rel="14"> </select> 日

 js部分：（此处需要引入jquery.js）

<script>
    $(function () {
        $.ms_DatePicker({
            YearSelector: ".sel_year",
            MonthSelector: ".sel_month",
            DaySelector: ".sel_day"
        });
    });
    (function($){
        $.extend({
            ms_DatePicker: function (options) {
                var defaults = {
                    YearSelector: "#sel_year",
                    MonthSelector: "#sel_month",
                    DaySelector: "#sel_day",
                    FirstText: "--",
                    FirstValue: 0
                };
                var opts = $.extend({}, defaults, options);
                var $YearSelector = $(opts.YearSelector);
                var $MonthSelector = $(opts.MonthSelector);
                var $DaySelector = $(opts.DaySelector);
                var FirstText = opts.FirstText;
                var FirstValue = opts.FirstValue;

                // 初始化
                var str = "<option value="" + FirstValue + "">"+FirstText+"</option>";
                $YearSelector.html(str);
                $MonthSelector.html(str);
                $DaySelector.html(str);

                // 年份列表
                var yearNow = new Date().getFullYear();
                var yearSel = $YearSelector.attr("rel");
                for (var i = yearNow; i >= 1900; i--) {
                    var sed = yearSel==i?"selected":"";
                    var yearStr = "<option value="" + i + "" " + sed+">"+i+"</option>";
                    $YearSelector.append(yearStr);
                }

                // 月份列表
                var monthSel = $MonthSelector.attr("rel");
                for (var i = 1; i <= 12; i++) {
                    var sed = monthSel==i?"selected":"";
                    var monthStr = "<option value="" + i + "" "+sed+">"+i+"</option>";
                    $MonthSelector.append(monthStr);
                }

                // 日列表(仅当选择了年月)
                function BuildDay() {
                    if ($YearSelector.val() == 0 || $MonthSelector.val() == 0) {
                        // 未选择年份或者月份
                        $DaySelector.html(str);
                    } else {
                        $DaySelector.html(str);
                        var year = parseInt($YearSelector.val());
                        var month = parseInt($MonthSelector.val());
                        var dayCount = 0;
                        switch (month) {
                            case 1:
                            case 3:
                            case 5:
                            case 7:
                            case 8:
                            case 10:
                            case 12:
                                dayCount = 31;
                                break;
                            case 4:
                            case 6:
                            case 9:
                            case 11:
                                dayCount = 30;
                                break;
                            case 2:
                                dayCount = 28;
                                if ((year % 4 == 0) && (year % 100 != 0) || (year % 400 == 0)) {
                                    dayCount = 29;
                                }
                                break;
                            default:
                                break;
                        }

                        var daySel = $DaySelector.attr("rel");
                        for (var i = 1; i <= dayCount; i++) {
                            var sed = daySel==i?"selected":"";
                            var dayStr = "<option value="" + i + "" "+sed+">" + i + "</option>";
                            $DaySelector.append(dayStr);
                        }
                    }
                }
                $MonthSelector.change(function () {
                    BuildDay();
                });
                $YearSelector.change(function () {
                    BuildDay();
                });
                if($DaySelector.attr("rel")!=""){
                    BuildDay();
                }
            } // End ms_DatePicker
        });
    })(jQuery);
</script>