sheetjs/bits/50_date.js

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;
	fixopts(opts != null ? opts : (opts=[]));
	if(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;
/*jshint -W086 */
function write_date(type/*:number*/, fmt/*:string*/, val, ss0/*:?number*/)/*:string*/ {
	var o="", ss=0, tt=0, y = val.y, out, outl = 0;
	switch(type) {
		case 98: /* 'b' buddhist year */
			y = val.y + 543;
			/* falls through */
		case 121: /* 'y' year */
		switch(fmt.length) {
			case 1: case 2: out = y % 100; outl = 2; break;
			default: out = y % 10000; outl = 4; break;
		} break;
		case 109: /* 'm' month */
		switch(fmt.length) {
			case 1: case 2: out = val.m; outl = fmt.length; break;
			case 3: return months[val.m-1][1];
			case 5: return months[val.m-1][0];
			default: return months[val.m-1][2];
		} break;
		case 100: /* 'd' day */
		switch(fmt.length) {
			case 1: case 2: out = val.d; outl = fmt.length; break;
			case 3: return days[val.q][0];
			default: return days[val.q][1];
		} break;
		case 104: /* 'h' 12-hour */
		switch(fmt.length) {
			case 1: case 2: out = 1+(val.H+11)%12; outl = fmt.length; break;
			default: throw 'bad hour format: ' + fmt;
		} break;
		case 72: /* 'H' 24-hour */
		switch(fmt.length) {
			case 1: case 2: out = val.H; outl = fmt.length; break;
			default: throw 'bad hour format: ' + fmt;
		} break;
		case 77: /* 'M' minutes */
		switch(fmt.length) {
			case 1: case 2: out = val.M; outl = fmt.length; break;
			default: throw 'bad minute format: ' + fmt;
		} break;
		case 115: /* 's' seconds */
		if(val.u === 0) switch(fmt) {
			case 's': case 'ss': return pad0(val.S, fmt.length);
			case '.0': case '.00': case '.000':
		}
		switch(fmt) {
			case 's': case 'ss': case '.0': case '.00': case '.000':
				/*::if(!ss0) ss0 = 0; */
				if(ss0 >= 2) tt = ss0 === 3 ? 1000 : 100;
				else tt = ss0 === 1 ? 10 : 1;
				ss = Math.round((tt)*(val.S + val.u));
				if(ss >= 60*tt) ss = 0;
				if(fmt === 's') return ss === 0 ? "0" : ""+ss/tt;
				o = pad0(ss,2 + ss0);
				if(fmt === 'ss') return o.substr(0,2);
				return "." + o.substr(2,fmt.length-1);
			default: throw 'bad second format: ' + fmt;
		}
		case 90: /* 'Z' absolute time */
		switch(fmt) {
			case '[h]': case '[hh]': out = val.D*24+val.H; break;
			case '[m]': case '[mm]': out = (val.D*24+val.H)*60+val.M; break;
			case '[s]': case '[ss]': out = ((val.D*24+val.H)*60+val.M)*60+Math.round(val.S+val.u); break;
			default: throw 'bad abstime format: ' + fmt;
		} outl = fmt.length === 3 ? 1 : 2; break;
		case 101: /* 'e' era */
			out = y; outl = 1;
	}
	if(outl > 0) return pad0(out, outl); else return "";
}
/*jshint +W086 */