# JavaScript calculates the day difference of of between two dates

• 2020-03-30 01:06:33
• OfStack

One: calculate the number of days between two dates

For example:
Str1   =   "2002-01-20"
Str2   =   "2002-10-11"
How do you calculate the number of days between str1 and str2 using javaScript?

``````
<html>
<meta  http-equiv="Content-Type"  content="text/html;  charset=gb2312">
<title></title>

<body>
<button  onClick="btnCount_Click()"> Counting days off </button>
<script  language="JavaScript">

function  btnCount_Click(){
s1  =  "2002-1-10"
s2  =  "2002-10-1"
}

//A function of the number of days, universal & PI;
function  DateDiff(sDate1,  sDate2){    //SDate1 and sDate2 are in 2002-12-18 format & NBSP;
oDate1  =  new  Date(aDate  +  '-'  +  aDate  +  '-'  +  aDate)    //Convert to 12-18-2002 & NBSP;
iDays  =  parseInt(Math.abs(oDate1  -  oDate2)  /  1000  /  60  /  60  /24)    //Converts the number of milliseconds off into the number of days & NBSP;
return  iDays
}
``````

Two: calculate the date after a certain number of days

In JavaScript, you calculate what the days after the date of the day are. Far from being as convenient as it is in.net, a function can solve the problem. On this problem, I puzzled for a period of time, and finally through the introduction of a net friend to solve the problem. Post it and share it.

``````
<script  language="javascript"  type="text/javascript">
var  startDate  =  new  Date  ();           var  intValue  =  0;
var  endDate  =  null;

intValue  =  startDate.getTime();            intValue  +=  100  *  (24  *  3600  *  1000);
endDate  =  new  Date  (intValue);
</script>
``````

The 100 above represents the date after 100 days, which you can change. Date.getTime() in JS, can only be 1970.01.01 after the Date; There are months are 0-11, a little different, avoid oh. Of course, you can also calculate the date after a certain date.
``````
<script  language="javascript"  type="text/javascript">
var  startDate  =  new  Date  (2007,  (8-1),  1,  10,  10,  10);
var  intValue  =  0;
var  endDate  =  null;

intValue  =  startDate.getTime();            intValue  +=  100  *  (24  *  3600  *  1000);
endDate  =  new  Date  (intValue);