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@gilly3
Last active August 31, 2020 15:44
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JavaScript date formatting function, loosely based on .Net's `String.Format()` for `DateTime`.
export default function formatDate(date, format, utc)
{
var MMMM = ["\x00", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
var MMM = ["\x01", "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
var dddd = ["\x02", "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
var ddd = ["\x03", "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
function ii(i, len) { var s = i + ""; len = len || 2; while (s.length < len) s = "0" + s; return s; }
var y = utc ? date.getUTCFullYear() : date.getFullYear();
format = format.replace(/(^|[^\\])yyyy+/g, "$1" + y);
format = format.replace(/(^|[^\\])yy/g, "$1" + y.toString().substr(2, 2));
format = format.replace(/(^|[^\\])y/g, "$1" + y);
var M = (utc ? date.getUTCMonth() : date.getMonth()) + 1;
format = format.replace(/(^|[^\\])MMMM+/g, "$1" + MMMM[0]);
format = format.replace(/(^|[^\\])MMM/g, "$1" + MMM[0]);
format = format.replace(/(^|[^\\])MM/g, "$1" + ii(M));
format = format.replace(/(^|[^\\])M/g, "$1" + M);
var d = utc ? date.getUTCDate() : date.getDate();
format = format.replace(/(^|[^\\])dddd+/g, "$1" + dddd[0]);
format = format.replace(/(^|[^\\])ddd/g, "$1" + ddd[0]);
format = format.replace(/(^|[^\\])dd/g, "$1" + ii(d));
format = format.replace(/(^|[^\\])d/g, "$1" + d);
var H = utc ? date.getUTCHours() : date.getHours();
format = format.replace(/(^|[^\\])HH+/g, "$1" + ii(H));
format = format.replace(/(^|[^\\])H/g, "$1" + H);
var h = H > 12 ? H - 12 : H == 0 ? 12 : H;
format = format.replace(/(^|[^\\])hh+/g, "$1" + ii(h));
format = format.replace(/(^|[^\\])h/g, "$1" + h);
var m = utc ? date.getUTCMinutes() : date.getMinutes();
format = format.replace(/(^|[^\\])mm+/g, "$1" + ii(m));
format = format.replace(/(^|[^\\])m/g, "$1" + m);
var s = utc ? date.getUTCSeconds() : date.getSeconds();
format = format.replace(/(^|[^\\])ss+/g, "$1" + ii(s));
format = format.replace(/(^|[^\\])s/g, "$1" + s);
var f = utc ? date.getUTCMilliseconds() : date.getMilliseconds();
format = format.replace(/(^|[^\\])fff+/g, "$1" + ii(f, 3));
f = Math.round(f / 10);
format = format.replace(/(^|[^\\])ff/g, "$1" + ii(f));
f = Math.round(f / 10);
format = format.replace(/(^|[^\\])f/g, "$1" + f);
var T = H < 12 ? "AM" : "PM";
format = format.replace(/(^|[^\\])TT+/g, "$1" + T);
format = format.replace(/(^|[^\\])T/g, "$1" + T.charAt(0));
var t = T.toLowerCase();
format = format.replace(/(^|[^\\])tt+/g, "$1" + t);
format = format.replace(/(^|[^\\])t/g, "$1" + t.charAt(0));
var tz = -date.getTimezoneOffset();
var K = utc || !tz ? "Z" : tz > 0 ? "+" : "-";
if (!utc) {
tz = Math.abs(tz);
var tzHrs = Math.floor(tz / 60);
var tzMin = tz % 60;
K += ii(tzHrs) + ":" + ii(tzMin);
}
format = format.replace(/(^|[^\\])K/g, "$1" + K);
var day = (utc ? date.getUTCDay() : date.getDay()) + 1;
format = format.replace(new RegExp(dddd[0], "g"), dddd[day]);
format = format.replace(new RegExp(ddd[0], "g"), ddd[day]);
format = format.replace(new RegExp(MMMM[0], "g"), MMMM[M]);
format = format.replace(new RegExp(MMM[0], "g"), MMM[M]);
format = format.replace(/\\(.)/g, "$1");
return format;
};
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