JS Implementation date Cascade effect

  This article is mainly on the implementation of the date of JS, the example of the effect of the introduction, the need for friends can come to the reference, I hope to help you.

The code is as follows:     <div>         <select name= "YYYY" onchange= "Yyyymm (this.value)" > &nbs P           <option value= "> Please select year </option>         </select>         <select name= "MM" onchange= "MMDD (this.value)" >           &NBSP ; <option value= "" > select month </option>         </select>         <sel ECT name= "DD" >             <option value= "> select day </option>     &NBSP ;   </select>     </div>       <script language= "JavaScript" >         Function window.onload () {            STRYYYY = Document.form1.YYYY.outerHTM L             STRMM = Document.form1.MM.outerHTML;             STRDD = document. Form1. dd.outerhtml;             Monhead = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];              ///First Nianxia box assignment             var y = new Date (). getFullYear ();             var str = stryyyy.substring (0, stryyyy.length-9);             for (var i = (y-30); i < (y +); i++)//To this year, the first 30 years, after 30 years     &NB Sp       {                str = "<option value= '" + i + "' >" + i + "year" + "</option>rn";                         Document.form1.YYYY.outerHTML = str + "</select>";              //Assign month Drop-down box             var str = Strmm.subst Ring (0, strmm.length-9);             for (var i = 1; i < i++} {                str = "<option value= '" + i + "' >" + i + "month" + "</ Option>rn ";                         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); Assignment Date dropdown box             Document.form1.DD.value = new Date (). GetDate ();         {        function yyyymm (str)//year change date changes (mainly judged leap excepting)   &NBS P     {          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)                   Fun ction MMDD (str)//monthly Change date linkage         {            var yyyyvalue = Docum Ent.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)//Conditional Write date dropdown box         {            var s = Strdd.s Ubstring (0, strdd.length-9);             for (var i = 1; i < (n + 1); i++)             & nbsp   S + + "<option value= '" + i + "' >" + i + "Day" + "</option>rn";             Document.form1.DD.outerHTML = s + "</select>";        }           function ispinyear (year)/determine if leap excepting       &N Bsp {            return (0 = year% 4 && (year%!= 0 | | year% = = 0))        }