javascript将字符串类型转换成日期进行比较

第一种适用于：20100823这种字符串格式
function dateValid(){
var bd = document.getElementById("sStartSaveDate").value;
var beginDate = new Date(bd.replace(/^(\d{4})(\d{2})(\d{2})$/,"$1/$2/$3"));

var ed = document.getElementById("sEndSaveDate").value;
var endDate = new Date(ed.replace(/^(\d{4})(\d{2})(\d{2})$/,"$1/$2/$3"));

if(beginDate >= endDate){
alert("结束时间必须大于开始时间！");
return false;
}else{
document.getElementById('searchform').submit();
}
}
第二种适用于：2010-08-23这种字符串格式
function dateValid(){
var beginDate = new Date(document.getElementById("sStartSaveDate").value.replace(/-/g,"/"));
var endDate = new Date(document.getElementById("sEndSaveDate").value.replace(/-/g,"/"));
if(beginDate >= endDate){
alert("结束时间必须大于开始时间！");
return false;
}else{
document.getElementById('searchform').submit();
}

第三种适用于：2010/08/23这种字符串格式
function dateValid(){
var beginDate = new Date(document.getElementById("sStartSaveDate").value);
var endDate = new Date(document.getElementById("sEndSaveDate").value);
if(beginDate >= endDate){
alert("结束时间必须大于开始时间！");
return false;
}else{
document.getElementById('searchform').submit();
}
}