<html><head><title>年月日三下拉框聯動</title><meta http-equiv='Content-Type' content='text/html; charset=gb2312'></head><body><form name=form1><select name=YYYY onchange="YYYYMM(this.value)"><option value="">請選擇 年</option></select><select name=MM onchange="MMDD(this.value)"><option value="">選擇 月</option></select><select name=DD><option value="">選擇 日</option></select></form><script language="JavaScript"><!--function window.onload(){strYYYY = document.form1.YYYY.outerHTML;strMM = document.form1.MM.outerHTML;strDD = document.form1.DD.outerHTML;MonHead = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];//先給年下拉框賦內容var y = new Date().getFullYear();var str = strYYYY.substring(0, strYYYY.length - 9);for (var i = (y-30); i < (y+30); i++) //以今年為準,前30年,後30年{str += "<option value='" + i + "'> " + i + " 年" + "</option>\r\n";}document.form1.YYYY.outerHTML = str +"</select>";//賦月份的下拉框var str = strMM.substring(0, strMM.length - 9);for (var i = 1; i < 13; i++){str += "<option value='" + i + "'> " + i + " 月" + "</option>\r\n";}document.form1.MM.outerHTML = str +"</select>";document.form1.YYYY.value = y;document.form1.MM.value = new Date().getMonth() + 1;var n = MonHead[new Date().getMonth()];if (new Date().getMonth() ==1 && IsPinYear(YYYYvalue)) n++;writeDay(n); //賦日期下拉框document.form1.DD.value = new Date().getDate();}function YYYYMM(str) //年發生變化時日期發生變化(主要是判斷閏平年){var MMvalue = document.form1.MM.options[document.form1.MM.selectedIndex].value;if (MMvalue == ""){DD.outerHTML = strDD; return;}var n = MonHead[MMvalue - 1];if (MMvalue ==2 && IsPinYear(str)) n++;writeDay(n)}function MMDD(str) //月發生變化時日期聯動{var YYYYvalue = document.form1.YYYY.options[document.form1.YYYY.selectedIndex].value;if (str == ""){DD.outerHTML = strDD; return;}var n = MonHead[str - 1];if (str ==2 && IsPinYear(YYYYvalue)) n++;writeDay(n)}function writeDay(n) //據條件寫日期的下拉框{var s = strDD.substring(0, strDD.length - 9);for (var i=1; i<(n+1); i++)s += "<option value='" + i + "'> " + i + " 日" + "</option>\r\n";document.form1.DD.outerHTML = s +"</select>";}function IsPinYear(year)//判斷是否閏平年{ return(0 == year%4 && (year0 !=0 || year%400 == 0))}//--></script></body></html>