Calculating a year time span

**Dman** · May 17th, 2004, 08:37 PM

How can I check to see that a date entered by the user is no more than one year from the current date? Better yet, any number of years entered. For instance, the user would enter a 2 year time span and determine if today's date falls within a two year time span.

**Acidic** · May 18th, 2004, 03:32 AM

Here's something I wrote a year or so ago. You can quite easily twek this to how you want it:

Code:

<html>
<head>
<title>Finds difference between two dates</title>
</head>
<body>
<form name="dateforms">
Starting date:<input name="one" type="text" value="24/02/1986">
in the format dd/mm/yyyy.<input name="onetime" type="text" value="03:30">
in the format hh:mm.<br>
Ending date:<input name="two" type="text" value="13/03/2003">
in the format dd/mm/yyyy.<input name="twotime" type="text" value="14:35">
in the format hh:mm.<br>
<input name="diff" type="text" value="[dates goes here]"><input name="difftime" type="text" value="[time goes here]"><br>
<input type="button" value="Calc" onClick="workout()">
</form>
<script language="javascript">
//This function can take characters from a string, used later.
function SubChars(_string,start,end) { 
return _string.substr(start,end-start); 
} 

function workout() {
var initdate=window.document.dateforms.one.value;
var enddate=window.document.dateforms.two.value;
var inittime=window.document.dateforms.onetime.value;
var endtime=window.document.dateforms.twotime.value;

// Getting the amount of day, months and years from textboxes.
var iday = SubChars(initdate,0,2);
var imonth = SubChars(initdate,3,5);
var iyear = SubChars(initdate,6,10);
var ihour = SubChars(inittime,0,2);
var imin = SubChars(inittime,3,5);
var fday = SubChars(enddate,0,2);
var fmonth = SubChars(enddate,3,5);
var fyear = SubChars(enddate,6,10);
var fhour = SubChars(endtime,0,2);
var fmin = SubChars(endtime,3,5);

//Calculations start here
if (fday-iday<1) {
	var fday = fday -1 + 31;
	var fmonth = fmonth - 1;
	}
var dday = fday-iday;

if (fmonth-imonth<1) {
	var fmonth = fmonth -1 + 13; //If I don't have -1 it does not work.
	var fyear = fyear - 1;
	}
var dmonth = fmonth-imonth;

var dyear = fyear-iyear;

if (dmonth > 11) {
	dyear = dyear-1+2; // Here too I must subtract one first.
	dmonth = 0;
	}
if (dday > 30) {
	dmonth = dmonth -1+2; // Here I must subtract one first.
	dday = 0;
	}

// Now the time
if (fhour-ihour<1) {
	dday = dday -1;
	fhour = fhour -1+25;
	}
var dhour = fhour-ihour;
if (fmin-imin<1) {
	dhour = dhour -1;
	fmin = fmin -1+61;
	}
var dmin = fmin-imin;

//Now printing the results.
var dprint = dday + "/" + dmonth + "/" + dyear;
window.document.dateforms.diff.value = dprint;	
//and the time...
var dprinttime = dhour + ":" + dmin;
window.document.dateforms.difftime.value = dprinttime;	
}
</script>
</body>
</html>

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