js判断选择时间不能小于当前时间的示例代码

var controldate; 
function checkDate(){ 
controldate= document.getElementById("sendDate").value; 
if(controldate==""){ 
alert('日期不能为空'); 
return false; 
}else{ 
var day = new Date(); var Year = 0; 
var Month = 0; 
var Day = 0; 
var CurrentDate = ""; 
//初始化时间 
Year = day.getFullYear(); 
Month = day.getMonth()+1; 
Day = day.getDate(); 

CurrentDate += Year + "-"; 

if (Month >= 10 ) 
{ 
CurrentDate += Month + "-"; 
} 
else 
{ 
CurrentDate += "0" + Month + "-"; 
} 
if (Day >= 10 ) 
{ 
CurrentDate += Day ; 
} 
else 
{ 
CurrentDate += "0" + Day ; 
} //alert(CurrentDate);//当前日期 

var startDate = new Date(CurrentDate.replace("-",",")).getTime() ; 
var endDate = new Date(controldate.replace("-",",")).getTime() ; if( startDate > endDate ) 
{ 
alert('选择日期不能小于当前日期！'); 
document.getElementById("sendDate").focus(); 
return false; 
}else{ 
return true; 
} 
} 
}