Web Development

19-Jul-04 20:34

Hi all,

Please anyone knows how to add day to a Date excluding weekends, preferrable language is Javascript.

function DateAdd(startDate, numDays, numMonths, numYears)<br />
{<br />
	var returnDate = new Date(startDate.getTime()) ;<br />
	var yearsToAdd = numYears ;	<br />
	var month = returnDate.getMonth() + numMonths + 1 ;<br />
	<br />
	if ( month > 11 )<br />
	{<br />
		yearsToAdd = Math.floor((month+1)/12) ;<br />
		<br />
		month -= 12*yearsToAdd ;<br />
		<br />
		yearsToAdd += numYears ;<br />
	}<br />
	<br />
	returnDate.setMonth(month) ;<br />
	<br />
	returnDate.setFullYear(returnDate.getFullYear()	+ yearsToAdd) ;<br />
	<br />
	returnDate.setTime(returnDate.getTime()+60000*60*24*numDays) ;<br />
	<br />
	return returnDate ;<br />
}

Now I need to exclude non-working days, i.e Thursday and Friday.

Help kindly appreciated.

Thanks

The Phantom.

Alexander Wiseman20-Jul-04 4:29

20-Jul-04 4:29

Hi,

I think this algorithm should work for what you are trying to do (it assumes that Thursday and Friday are the "non-work days":

<br />
function DateAdd(startDate, numDays, numMonths, numYears)<br />
{<br />
var returnDate = new Date(startDate.getTime()) ;<br />
var yearsToAdd = numYears ; <br />
var month = returnDate.getMonth() + numMonths + 1 ;<br />
<br />
if ( month > 11 )<br />
{<br />
yearsToAdd = Math.floor((month+1)/12) ;<br />
month -= 12*yearsToAdd ;<br />
yearsToAdd += numYears ;<br />
}<br />
<br />
returnDate.setMonth(month) ;<br />
returnDate.setFullYear(returnDate.getFullYear() + yearsToAdd) ;<br />
<br />
// Before we add the days, make sure to exclude non-work days:<br />
var finalDays = 0;<br />
if(numDays >= 5)<br />
{<br />
    //Since you have 2 non-work days, you basically have a 5-day week:<br />
    var weeks = (numDays / 5);<br />
    finalDays = (weeks * 7);<br />
    numDays -= (weeks * 5);<br />
}<br />
<br />
// numDays is now less than 5:<br />
if(numDays > 0)<br />
{<br />
    var dayOfWeek = returnDate.getDay();<br />
   <br />
    // See if, adding the days, we land on or pass any non-work days:<br />
    if(dayOfWeek < 4 && (dayOfWeek + numDays) >= 4)<br />
    {<br />
        finalDays += (numDays + 2); //effectively skips Thursday and Friday<br />
    }<br />
    else<br />
    {<br />
	if(dayOfWeek == 4 || dayOfWeek == 5)<br />
        {<br />
            finalDays += (numDays + (5-dayOfWeek));<br />
        }<br />
        else<br />
            finalDays += numDays;<br />
    }<br />
}<br />
<br />
// Now finalDays contains the number of days we want to add:<br />
returnDate.setTime(returnDate.getTime()+60000*60*24*finalDays);<br />
<br />
return returnDate;<br />
}<br />

I didn't test the code, but I think it should work. Let me know if it doesn't, or if you have more questions.

[EDIT]
Sorry, slight mistake in the function if dayOfWeek = 6. Now it is fixed
[/EDIT]

Sincerely,
Alexander Wiseman

Est melior esse quam videri
It is better to be than to seem

Ph@ntom20-Jul-04 16:59

20-Jul-04 16:59

Alexander Wiseman,

Your forumula worked.

Five points for you.

Cheers Wink | ;)

,

Regards,

The Phantom.

Ph@ntom20-Jul-04 19:13

20-Jul-04 19:13

Alexander,

Buddy, sometimes it doesnot work.

What this logic is simply doing is after taking 7 seven days into consideration it simply deducts 2 days, and after doing this, it sometimes skips the working days as well.

Please help me out.

Best Regards,

The Phantom.

Alexander Wiseman21-Jul-04 3:31

21-Jul-04 3:31

Hey,

I tested the function today and realized I made a mistake in the calculate of weeks.

My line read var weeks = (numDays / 5);. When I wrote this I was thinking in C++ mode, thinking that the division operator would only return a whole number. In Javascript it returns the exact quotient, so we simply need to add the Math.floor function so it looks like this: var weeks = Math.floor(numDays / 5).

Give that a try and see if it works for you. Also, I ran across another problem in your section of the function. You have this line: var month = returnDate.getMonth() + numMonths + 1;. I think that the + 1 is unnecessary and returns the wrong date.

Make those two changes and it should be working for you! I didn't do extensive testing, so if you find any other strange scenarios which don't work, please tell me and I would be happy to correct the code.

Sincerely,
Alexander Wiseman

Est melior esse quam videri
It is better to be than to seem

Ph@ntom23-Jul-04 17:48

23-Jul-04 17:48

Alex,

I've done those two changes accordingly, still some places it includes Thursday's and Friday's.

Please have a look.

Regards,

The Phantom.

Alexander Wiseman25-Jul-04 3:22

25-Jul-04 3:22

Okay, I figured it out and this time I've tested it. The remaining problem was caused under these conditions:

1) The startDate is a Thursday or a Friday
2) The number of days being added is a multiple of 5

In this case, the algorithm would always return a Thursday or Friday because it would simple add 7*(number of times 5 goes into numDays). To fix this, all I added was another "else" clause which checked this case and fixed it. Below is the final function:

// Function DateAdd: adds a number of non-work days and a number of months and years
// to a given date
function DateAdd(startDate, numDays, numMonths, numYears)
{
var returnDate = new Date(startDate.getTime()) ;
var yearsToAdd = numYears ; 
var month = returnDate.getMonth() + numMonths;

if ( month > 11 )
{
	yearsToAdd = Math.floor((month+1)/12) ;
	month -= 12*yearsToAdd ;
	yearsToAdd += numYears ;
}

returnDate.setMonth(month) ;
returnDate.setFullYear(returnDate.getFullYear() + yearsToAdd) ;

// Before we add the days, make sure to exclude non-work days:
var finalDays = 0;
if(numDays >= 5)
{
	//Since you have 2 non-work days, you basically have a 5-day week:
	var weeks = Math.floor((numDays / 5));
	finalDays = (weeks * 7);
	numDays -= (weeks * 5);
}

// numDays is now less than 5:
var dayOfWeek = returnDate.getDay();
if(numDays > 0)
{

	// See if, adding the days, we land on or pass any non-work days:
	if(dayOfWeek < 4 && (dayOfWeek + numDays) >= 4)
	{
		finalDays += (numDays + 2); //effectively skips Thursday and Friday
	}
	else
	{
		if(dayOfWeek == 4 || dayOfWeek == 5)
		{
			finalDays += (numDays + (5-dayOfWeek));
		}
		else
			finalDays += numDays;
	}

}
else
{
	//This is the odd case: where we started on a work day and numDays is evenly divisible by 5:
	if(dayOfWeek == 4 || dayOfWeek == 5)
	{
		finalDays -= (dayOfWeek - 3);
	}
}

// Now finalDays contains the number of days we want to add:
returnDate.setTime(returnDate.getTime()+60000*60*24*finalDays);
return returnDate;

}

Hope that works for you. I apologize for the mistakes.

Sincerely,
Alexander Wiseman

Ph@ntom25-Jul-04 6:16

25-Jul-04 6:16

Alex,

The way you help for writing this snippet is more than the success factor for the snippet.

I really appreciate for your help and you don't need to make the apologize.

I was trying for the whole day on the logic I was thinking on, I made it work but the logic was not efficient enough and it was slowing down the system and eating the memory resources. But I thought you will come up the solution.

Alright, I've tried the code and this time it works Wink | ;)

but

it doesn't work where I need to get the back days, I mean instead of addition I tried to do subtraction of days, it never works for the condition but when I try to change the code:

if(numDays > 0) to if(numDays > 0 || numDay < 0) to make subtraction work it again took Thursday and Friday.

In the mean time, if you've some time then there is a reverse situaion where I need to calculate the difference between two dates excluding the same non-working days, I already submitted a Thread with the reference:

Calculating Variance excluding non-working days busisoft 23:03 20 Jul '04

Thanks again for your kind help.

Regards,

The Phantom.

Ph@ntom26-Jul-04 6:12

26-Jul-04 6:12

Alex,

Please first check this out.

As you said i made the changes, but it only works when I remove the 1 from calculating the month, remember I was adding 1 in calculating month. Now when I remove the 1 it works but what will happen it goes back to the month , for example if the selected date was 26/07/2004 and if we add 1 then it shows 27/06/2004.

Please check it out what's happening.

Thanks.

Regards,

The Phantom.

Alexander Wiseman27-Jul-04 8:00

27-Jul-04 8:00

Hi,

I pasted the function source from my post above into a webpage and tested the scenario you mentioned, but, oddly enough, I didn't have the same problem. Maybe check to see if your function is identical to the one I posted above and then, if that doesn't work, give me the exact code where you invoke the function.

I will look at DateVariance when I have a chance.

Sincerely,
Alexander Wiseman

Ph@ntom27-Jul-04 19:40

27-Jul-04 19:40

First I found that javascript function getMonth() always starts from zero

I copied it as it is from the above reply!

This is the place where I am calling it

FormatDate(AddDayToDate(FormatDate(document.frmEngine.PLREMDATE.value,"yyyy/mm/dd"), 0), "dd/mm/yyyy") ;

// Definition of AddDayToDate<br />
function AddDayToDate(plandate, days)<br />
{<br />
	var gCurrentDate = new Date(plandate)<br />
	<br />
		var newDate = DateAdd(gCurrentDate, parseInt(days,10), <br />
						parseInt(0,10), <br />
						parseInt(0,10));	<br />
			<br />
	var year = newDate.getFullYear()  ; <br />
	var month = newDate.getMonth() ;<br />
	var date = newDate.getDate() ;<br />
	return date + "/" + month + "/" + year ;<br />
}

// Definition of FormatDate function<br />
function FormatDate(DateToFormat,FormatAs)<br />
{<br />
	if(DateToFormat=="")<br />
	{<br />
		return"";<br />
	}<br />
	<br />
	if(!FormatAs){FormatAs="dd/mm/yyyy";}<br />
<br />
	var strReturnDate;<br />
	<br />
	FormatAs = FormatAs.toLowerCase();<br />
	<br />
	DateToFormat = DateToFormat.toLowerCase();<br />
	<br />
	var arrDate<br />
	<br />
	var arrMonths = new Array("January","February","March","April","May","June","July","August","September","October","November","December");<br />
	<br />
	var strMONTH;<br />
	<br />
	var Separator;<br />
<br />
	while(DateToFormat.indexOf("st")>-1)<br />
	{	<br />
		DateToFormat = DateToFormat.replace("st","");<br />
	}<br />
<br />
	while(DateToFormat.indexOf("nd")>-1)<br />
	{<br />
		DateToFormat = DateToFormat.replace("nd","");<br />
	}<br />
<br />
	while(DateToFormat.indexOf("rd")>-1)<br />
	{<br />
		DateToFormat = DateToFormat.replace("rd","");<br />
	}<br />
<br />
	while(DateToFormat.indexOf("th")>-1)<br />
	{<br />
		DateToFormat = DateToFormat.replace("th","");<br />
	}<br />
<br />
	if(DateToFormat.indexOf(".")>-1)<br />
	{<br />
		Separator = ".";<br />
	}<br />
<br />
	if(DateToFormat.indexOf("-")>-1)<br />
	{<br />
		Separator = "-";<br />
	}<br />
<br />
<br />
	if(DateToFormat.indexOf("/")>-1)<br />
	{<br />
		Separator = "/";<br />
	}<br />
<br />
	if(DateToFormat.indexOf(" ")>-1)<br />
	{<br />
		Separator = " ";<br />
	}<br />
<br />
	arrDate = DateToFormat.split(Separator);<br />
	DateToFormat = "";<br />
<br />
	for(var iSD = 0;iSD < arrDate.length;iSD++)<br />
	{<br />
		if(arrDate[iSD]!="")<br />
		{<br />
			DateToFormat += arrDate[iSD] + Separator;<br />
		}<br />
	}<br />
	<br />
	DateToFormat = DateToFormat.substring(0,DateToFormat.length-1);<br />
	arrDate = DateToFormat.split(Separator);<br />
<br />
	if(arrDate.length < 3)<br />
	{<br />
		return "";<br />
	}<br />
<br />
	var DAY = arrDate[0];<br />
	var MONTH = arrDate[1];<br />
	var YEAR = arrDate[2];<br />
<br />
	if(parseFloat(arrDate[1]) > 12)<br />
	{<br />
		DAY = arrDate[1];<br />
		MONTH = arrDate[0];<br />
	}<br />
<br />
	if(parseFloat(DAY) && DAY.toString().length==4)<br />
	{<br />
		YEAR = arrDate[0];<br />
		DAY = arrDate[2];<br />
		MONTH = arrDate[1];<br />
	}<br />
<br />
<br />
	for(var iSD = 0;iSD < arrMonths.length;iSD++)<br />
	{<br />
		var ShortMonth = arrMonths[iSD].substring(0,3).toLowerCase();<br />
		var MonthPosition = DateToFormat.indexOf(ShortMonth);<br />
		if(MonthPosition > -1)<br />
		{<br />
			MONTH = iSD + 1;<br />
			if(MonthPosition == 0)<br />
			{<br />
				DAY = arrDate[1];<br />
				YEAR = arrDate[2];<br />
			}<br />
			break;<br />
		}<br />
	}<br />
<br />
	var strTemp = YEAR.toString();<br />
<br />
	if(strTemp.length==2)<br />
	{<br />
		if(parseFloat(YEAR)>40)<br />
		{<br />
			YEAR = "19" + YEAR;<br />
		}<br />
		else<br />
		{<br />
			YEAR = "20" + YEAR;<br />
		}<br />
	}<br />
<br />
<br />
	if(parseInt(MONTH)< 10 && MONTH.toString().length < 2)<br />
	{<br />
		MONTH = "0" + MONTH;<br />
	}<br />
	<br />
	if(parseInt(DAY)< 10 && DAY.toString().length < 2)<br />
	{<br />
		DAY = "0" + DAY;<br />
	}<br />
	<br />
	switch (FormatAs)<br />
	{<br />
		case "dd/mm/yyyy":<br />
			return DAY + "/" + MONTH + "/" + YEAR;<br />
		case "mm/dd/yyyy":<br />
			return MONTH + "/" + DAY + "/" + YEAR;<br />
		case "dd/mmm/yyyy":<br />
			return DAY + " " + arrMonths[MONTH -1].substring(0,3) + " " + YEAR;<br />
		case "mmm/dd/yyyy":<br />
			return arrMonths[MONTH -1].substring(0,3) + " " + DAY + " " + YEAR;<br />
		case "dd/mmmm/yyyy":<br />
			return DAY + " " + arrMonths[MONTH -1] + " " + YEAR;	<br />
		case "mmmm/dd/yyyy":<br />
			return arrMonths[MONTH -1] + " " + DAY + " " + YEAR;<br />
		case "yyyy/mm/dd":<br />
			return YEAR + " " + arrMonths[MONTH -1] + " " + DAY ;<br />
	}<br />
<br />
	return DAY + "/" + strMONTH + "/" + YEAR;;<br />
<br />
} //End Function

Regards,

The Phantom.

Alexander Wiseman28-Jul-04 4:31

28-Jul-04 4:31

Hey,

I have looked through your code and discovered why the month is being decreased by 1. You were exactly right when you said that the getMonth() function returns the zero-based index of the month. Your formatting functions assume a one-based index of the month, which means that the when you call FormatDate after the call to AddDayToDate, the month gets set back by 1 (July becomes June, in your test scenario).

Fortunately, there is an easy way to fix this and I have tested it to make sure it works. You need to modify the AddDayToDate function to add one to the month returned by getMonth. Below you will find the modified version of AddDayToDate. Copy it into your code and it should work fine.

// Definition of AddDayToDate
function AddDayToDate(plandate, days)
{
    var gCurrentDate = new Date(plandate);

    var newDate = DateAdd(gCurrentDate, parseInt(days,10), 
    parseInt(0,10), 
    parseInt(0,10)); 

    var year = newDate.getFullYear() ; 

    //The changed line: note the +1 to get the month in a one based index
    var month = newDate.getMonth() + 1 ;

    var date = newDate.getDate() ;

    return date + "/" + month + "/" + year ;
}

Hope that helps! Let me know if it still doesn't work. Also, I haven't had a chance, but I plan to work on the DateVariance function. I already know how to go about it, so it will just be a matter of sitting down and writing the code when I have a free moment.

Sincerely,
Alexander Wiseman

Ph@ntom30-Jul-04 18:57

30-Jul-04 18:57

Alex,

It worked.

5 stars for you Wink | ;)

Please, look for the day variance as I am loosing my patience Smile | :)

Thanks.

Regards,

The Phantom.

Alexander Wiseman2-Aug-04 7:15