thdoan / strftime Goto Github PK

Love this library! I use it all the time in preference to what I consider the incomprehensible and poorly-documented Javascript Date formatters. But the one thing I can't do is get the abbreviate timezone, which I basically always want. The strftime %Z option supposedly returns "the timezone name or abbreviation," which are two very different strings -- e.g. "Eastern Daylight Time" vs "EDT". In practice, it always seems to be the longer version, but either way, since I can't rely on the output, the %Z is worthless to me (and I would imagine the majority of web developers).

The same issue of course occurs in the Unix strftime -- the problem doesn't originate with this library.

So I end up writing my own ugly wrappers around strftime to stitch this in everywhere:

export function shortTz(date?: Date | null): string | undefined {
  if (!date) { return undefined }
  const timeString = date.toLocaleTimeString('en', {timeZoneName: 'short'})
  return timeString.match(' ([A-Z+0-9]+)$')![1]!
}

export function formatTimeWithShortTz(format: string, time: Date): string {
  return `${stftime(format, time)} ${shortTz(time)}`
}

Though strftime is intended to be a port of the Unix version, this one simple enhancement to me vastly increases its usefulness. Would it be possible to extend it to cover this case, with the understanding that abbreviations aren't standardized and may be browser-dependent? Since %Z is non-deterministic anyway, changing it return the abbreviated time zone (which seems more useful and common than the spelled-out one) would not break backwards compatibility. Ideally we could add a second %something for the spelled-out case and cover both.

console.log(strftime("%Y_%m_%d_%H_%M_%S_", Date.now()));

@thdoan
Hello !

I came across your library while working on replacement for a deprecated Firefox function toLocaleFormat()

Your library is excellent and tiny!
Any problem using for a Thunderbird add-on? I will of course give attribution in the contributor section of the manifest. I think the license mixing with the Mozilla license should be okay.

Cheers and thanks in advance.
@cleidigh

Before checking for instanceof, date needs to be converted to Date object
and need to be checked for valid date just incase date is a null or empty string

function strftime(sFormat, sDate) {
	if (typeof sFormat !== 'string') {
	  return '';
	}
	if (sDate == "") {return sDate;}
	let date = new Date(sDate);
	if (!(date instanceof Date  && !isNaN(date))) {
	  return sDate;
	}

I think line 92 should read:

return zeroPad(1 + Math.ceil((n1stThu - target.valueOf()) / 604800000), 2);

rather than:

return zeroPad(1 + Math.ceil((n1stThu - target) / 604800000), 2);