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Kunst in huis? Netty Franssen maakt ook bijzonder mooie dingen | Day or Date of the Monday of a weekIncludes a working Javascript example at the bottom of this page |  |
I needed a Javascript function to get the beginning and ending dates of a week of a given year. Since I could not find one on the net, I googled for shorthands and looked up some of my old 3GL code I wrote back in 1992 (still functioning on iSeries, though) and put the two together into a Javascript function to get the date of the monday of a week, in some format. I copied the code from RPG III to Javascript so I have that functionality elsewhere, too.
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| Input year (YYYY): | and week | |
| Monday of the week is: | ||
| Day number: | mv_dateToString(mv_mondayOfWeek(selYY, selWW, 1), '%d-%Y') | |
| Date: | mv_dateToString(mv_mondayOfWeek(selYY, selWW, 0), '%d-%m-%Y') | |
| Last day of week: | var weekmsec = 1000*60*60*24*6; var d = new Date(); d.setTime(mv_mondayOfWeek(selYY, selWW, 2) + weekmsec); // add 6 days mv_dateToString(d, '%d-%m-%Y'); | |
Here’s the code (also all together in mv_clcdat.js):
function mv_leapck(yy, dorf) {
// dorf = 1=Days or 0=Flag
if(new Date(yy,1,29).getDate() == 29)
return(1 + (dorf==1 ? 365 : 0));
else
return(0 + (dorf==1 ? 365 : 0));
}
function mv_isDateObject(d) {
if (typeof d == 'object') {
if(d.getTime === undefined)
return(0);
else;
return(1);
} else
return(0);
}
function mv_dateToString(datum, format) {
/*
IN:
YYYYMMDD
YYYYDDD
YYYYWW or YYYYMM
or a date object
OUT:
Anything. Depends on format.
%d = day (DD or DDD)
%m = month
%w = week
%y = yy
%Y = yyyy
*/
var txt = '';
var fmt = new String(format);
if(mv_isDateObject(datum))
txt = new String(datum.getFullYear() * 10000 + (datum.getMonth() + 1) * 100 + datum.getDate());
else
txt = new String(datum);
if(txt.length >= 6) {
fmt = fmt.replace('%y', txt.substr(2,2));
fmt = fmt.replace('%Y', txt.substr(0,4));
if(txt.length == 8) {
fmt = fmt.replace('%m', txt.substr(4,2));
fmt = fmt.replace('%d', txt.substr(6,2));
}
else if(txt.length == 7)
fmt = fmt.replace('%d', txt.substr(4,3));
else if(txt.length == 6)
fmt = fmt.replace('%w', txt.substr(4,2));
}
return(fmt);
}
function mv_stringToDate(datum) {
/*
IN:
DD[-./]MM[-,/]YYYY
OUT:
YYYYMMDD
*/
orgdate = datum;
newdate = datum;
if(orgdate.length == 7) {
orgdate = '0' + orgdate;
}
else if(orgdate.length == 9) {
orgdate = '0' + orgdate;
}
newdate = orgdate.split("-").reverse().join("");
if(newdate == orgdate) {
newdate = orgdate.split(".").reverse().join("");
if(newdate == orgdate) {
newdate = orgdate.split("/").reverse().join("");
if(newdate == orgdate) {
newdate = orgdate.substr(4,4) + orgdate.substr(2,2) + orgdate.substr(0,2)
}
}
}
return(newdate);
}
function mv_mondayOfWeek(yy, ww, mdd) {
/*
MONDAY returns the day number or the date
of the monday in the week ww of year yy.
IN:
- 4-digit year
- weeknumber
- mdd = 2=Milliseconds, 1=Day or 0=Date
OUT:
- Day = YYYYDDD (DDD = Day number in year YYYY)
- Date = YYYYMMDD
*/
var daymsec = 1000*60*60*24;
var wrk1 = wrk2 = 0;
// Calculate offset
wrk1 = yy - 1900 + parseInt((yy - 1900 - 1) / 4);
wrk1 -= parseInt(wrk1 / 7) * 7;
if(wrk1 > 3) wrk1 -= 7;
wrk2 = (ww * 7) - wrk1 - 6;
if (wrk1 < 0 && ww == 53) {
yy--;
wrk2 -= 371;
wrk2 += mv_leapck(yy, 1);
}
else if (wrk2 <= 0) {
yy--;
wrk2 += mv_leapck(yy, 1);
}
// Format return value
if(isNaN(parseInt(mdd)) || parseInt(mdd) == 0) {
wrk1 = (new Date(yy-1, 11, 31)).getTime();
wrk1 += wrk2 * daymsec; // in milliseconds
wrk2 = new Date();
wrk2.setTime(wrk1); // Date of monday in week ww
wrk1 = wrk2.getFullYear() * 10000 + (wrk2.getMonth() + 1) * 100 + wrk2.getDate();
} else if(parseInt(mdd) == 2) {
wrk1 = (new Date(yy-1, 11, 31)).getTime();
wrk1 += wrk2 * daymsec; // in milliseconds
} else {
wrk1 = (yy * 1000) + wrk2;
}
return(wrk1); // Date or Day of monday
}
