sheetjs-clone/packages/ssf/bits/35_datecode.js

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function parse_date_code(v/*:number*/,opts/*:?any*/,b2/*:?boolean*/) {
if(v > 2958465 || v < 0) return null;
var date = (v|0), time = Math.floor(86400 * (v - date)), dow=0;
var dout=[];
var out={D:date, T:time, u:86400*(v-date)-time,y:0,m:0,d:0,H:0,M:0,S:0,q:0};
if(Math.abs(out.u) < 1e-6) out.u = 0;
if(opts && opts.date1904) date += 1462;
if(out.u > 0.9999) {
out.u = 0;
if(++time == 86400) { out.T = time = 0; ++date; ++out.D; }
}
if(date === 60) {dout = b2 ? [1317,10,29] : [1900,2,29]; dow=3;}
else if(date === 0) {dout = b2 ? [1317,8,29] : [1900,1,0]; dow=6;}
else {
if(date > 60) --date;
/* 1 = Jan 1 1900 in Gregorian */
var d = new Date(1900, 0, 1);
d.setDate(d.getDate() + date - 1);
dout = [d.getFullYear(), d.getMonth()+1,d.getDate()];
dow = d.getDay();
if(date < 60) dow = (dow + 6) % 7;
if(b2) dow = fix_hijri(d, dout);
}
out.y = dout[0]; out.m = dout[1]; out.d = dout[2];
out.S = time % 60; time = Math.floor(time / 60);
out.M = time % 60; time = Math.floor(time / 60);
out.H = time;
out.q = dow;
return out;
}
SSF.parse_date_code = parse_date_code;
var basedate = new Date(1899, 11, 31, 0, 0, 0);
var dnthresh = basedate.getTime();
var base1904 = new Date(1900, 2, 1, 0, 0, 0);
function datenum_local(v/*:Date*/, date1904/*:?boolean*/)/*:number*/ {
var epoch = v.getTime();
if(date1904) epoch -= 1461*24*60*60*1000;
else if(v >= base1904) epoch += 24*60*60*1000;
return (epoch - (dnthresh + (v.getTimezoneOffset() - basedate.getTimezoneOffset()) * 60000)) / (24 * 60 * 60 * 1000);
}