function CheckDate(str){
var reg = /^(\d{4})\/(\d{1,2})\/(\d{1,2})$/;
var r = str.match(reg);
if(r==null)return false;
r[2]=r[2]-1;
var d= new Date(r[1], r[2],r[3]);
if(d.getFullYear()!=r[1])return false;
if(d.getMonth()!=r[2])return false;
if(d.getDate()!=r[3])return false;
return true;
}