MediaWiki:Common.js

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/* Any JavaScript here will be loaded for all users on every page load. */
function initCountdown() {
  var reset = new Date();
  reset.setUTCHours(19, 0, 0, 0);
  
  function pad(n) {
    return ("0" + (n | 0)).slice(-2);
  }

  function tick() {
    var now = new Date();
    if (now > reset) {
      reset.setUTCDate(reset.getUTCDate() + 1);
    }
    var remaining = ((reset - now) /  1000);
    var hours = (remaining / 3600) % 60;
    var minutes = (remaining / 60) % 60;
    var seconds = remaining % 60;
    document.getElementById("resetCountdown").innerHTML = pad(hours) + ":" + pad(minutes) + ":" + pad(seconds);
    setTimeout(tick, 1000);
  }

  tick();
}
if(mw.config.get("wgPageName") === "Main_Page") {
  initCountdown();
}