String.prototype.isDate = function() { 
    var p; 
    var re1 = /(\d{4})[年./-](\d{1,2})[月./-](\d{1,2})[日]?$/; 
    var re2 = /(\d{1,2})[月./-](\d{1,2})[日./-](\d{2})[年]?$/; 
    var re3 = /(\d{1,2})[月./-](\d{1,2})[日./-](\d{4})[年]?$/; 
    if(re1.test(this)) { 
        p = re1.exec(this); 
        return new Date(p[1],p[2],p[3]); 
    } 
    if(re2.test(this)) { 
        p = re2.exec(this); 
        return new Date(p[3],p[1],p[2]);
    } 
    if(re3.test(this)) { 
        p = re3.exec(this); 
        return new Date(p[3],p[1],p[2]);
    } 
    return null; 
} 
var d = "2008-01-01".isDate();
alert(d);
alert("10-10-2009".isDate());
alert("13101-2009".isDate());

------解决方案--------------------
（另外如何支持  调用如何作
是否可以 var  mydate＝d(date_1)  还是  date mydate＝d(date_1) ？？
）  

var  mydate＝d(date_1) 即可。

------解决方案--------------------
var date1_day=date_1.chinese wholesalers
ugg(0,2);
 var date1_mon=date_1.substring(3,5);
 var date1_year=date_1.substring(6,10);

------解决方案--------------------
between : function(date, start, end){
   date = chinese wholesalers
uggparse(date); start = this.parse(start); end = this.parse(end);
   if (date && start && end) {  
     var t = date.getTime();
     return start.getTime() <= t && t <= end.getTime();