JavaScript每周五重复倒计时至中午

Question

Im after some code which will display days, hours and minutes which counts down the days, hours and minutes left til midday every Friday?

(When midday friday is reached I would like the counter to start again to countdown to the next Friday midday, so the timer repeats over and over?)

Not sure how to go about doing this as I am relatively new to JS

Any help much appreciated!

Answer 1

There are lots of questions here on timers and countdowns, you should be able to work out something basic from them. A very simple countdown to noon next Friday is:

 function update(){ // Get current date and time var today = new Date(); // Get number of days to Friday var dayNum = today.getDay(); var daysToFri = 5 - (dayNum < 5? dayNum : dayNum - 7); // Get milliseconds to noon friday var fridayNoon = new Date(+today); fridayNoon.setDate(fridayNoon.getDate() + daysToFri); fridayNoon.setHours(12,0,0,0); // Round up ms remaining so seconds remaining matches clock var ms = Math.ceil((fridayNoon - today)/1000)*1000; var d = ms / 8.64e7 | 0; var h = (ms % 8.64e7) / 3.6e6 | 0; var m = (ms % 3.6e6) / 6e4 | 0; var s = (ms % 6e4) / 1e3 | 0; // Return remaining return d + 'd ' + h + 'h ' + m + 'm ' + s + 's'; } // Run update just after next full second function runUpdate() { var el = document.getElementById('toFriday'); el.innerHTML = update(); setTimeout(runUpdate, 1020 - (Date.now()%1000)); } runUpdate(); 

 <div>Remaining to noon next Friday: <span id="toFriday"></span> 

This is a very basic implementation and will skip when it goes over a daylight saving boundary (which can be avoided), but it should suit for a simple countdown where the hours remaining is not critical. It will only be wrong for a short time:

• in places where daylight saving is observed,
• on the two days of the year where daylight saving changes have an effect, and
• if the change is not at midnight