原始Javascript中的双（多级）倒计时

Question

Okay, so this is driving me nuts.

I am trying to make a countdown that counts to a certain day of the week in a certain timezone... and once the timer hits zero then it changes the countdown timer's caption and counts down to another day of the week in a different timezone.

Basically, I need it to show when Saturday starts in a certain timezone... and when it's Saturday I need it to count down to when Sunday starts in a different timezone...

The idea is the two time-zones are the earliest and latest time-zones on either side of the international date line... so "it's Saturday somewhere for n more days/hours/minutes/seconds" vs. "it will be Saturday somewhere in n days/hours/minutes/seconds" -- it's actually "Saturday somewhere" for 50 hours.

I believe it's between 3am Friday and 5am Sunday in my timezone, so that is the border of "it's Saturday somewhere" -- this doesn't account for changes from daylight savings time.

Another issue is that people viewing the countdown timer won't all be in my timezone... so I'm thinking I might need to set it up to do a little math with the time-zone offset.

I feel like I'm over-thinking this. I've knit-picked my code to death and I just want to have a clean slate to hash this out from scratch.

Any help would be greatly appreciated.

Answer 1

Per comments above, here's what I came up with... trying to keep it clear what's actually happening... (Edit: corrected...)

var currentTime = new Date().valueOf();
var wktime = currentTime/604800000;
wktime -= Math.floor(wktime);
wktime *= 604800000;
wktime -= 122400000;//milliseconds from zero time to the original saturday, so 0 is the start of saturday.
var lengthOfSaturday = (24+12+14)*60*60*1000; //just to make the math clear
if (wktime > lengthOfSaturday) {
  var msToNextSaturday = wktime-lengthOfSaturday;
} else {
  var timeLeftSaturday = lengthOfSaturday-wktime;
}