更新以获得更多压缩

const formatAMPM = (date) => {
  let hours = date.getHours();
  let minutes = date.getMinutes();    
  const ampm = hours >= 12 ? 'pm' : 'am';

  hours %= 12;
  hours = hours || 12;    
  minutes = minutes < 10 ? `0${minutes}` : minutes;

  const strTime = `${hours}:${minutes} ${ampm}`;

  return strTime;
};

console.log(formatAMPM(new Date()));

   const formatAMPM = (date) => {
    try {
      let time = date.split(" ");
      let hours = time[4].split(":")[0];
      let minutes = time[4].split(":")[1];
      hours = hours || 12;
      const ampm = hours >= 12 ? " PM" : " AM";
      minutes = minutes < 10 ? `${minutes}` : minutes;
      hours %= 12;
      const strTime = `${hours}:${minutes} ${ampm}`;
      return strTime;
    } catch (e) {
      return "";
    }
  };

const startTime = "2021-12-07T17:00:00.073Z"
formatAMPM(new Date(startTime).toUTCString())

函数formatAMPM(date) { var hours = date.getHours(); var minutes = date.getMinutes(); Var ampm =小时>= 12 ?'pm': 'am'; 小时=小时% 12; 小时=小时?时长:12小时;//小时'0'应该是'12' 分钟=分钟< 10 ?'0'+minutes: minutes; var strTime = hours + ':' + minutes + ' + ampm; 返回strTime; ｝ console.log (formatAMPM(新日期));

en-US的短RegExp:

var d = new Date();
d = d.toLocaleTimeString().replace(/:\d+ /, ' '); // current time, e.g. "1:54 PM"

<h1 id="clock_display" class="text-center" style="font-size:40px; color:#ffffff">[CLOCK TIME DISPLAYS HERE]</h1>



<script>
            var AM_or_PM = "AM";

            function startTime(){

                var today = new Date();
                var h = today.getHours();
                var m = today.getMinutes();
                var s = today.getSeconds();

                h = twelve_hour_time(h);
                m = checkTime(m);
                s = checkTime(s);



                document.getElementById('clock_display').innerHTML =
                    h + ":" + m + ":" + s +" "+AM_or_PM;
                var t = setTimeout(startTime, 1000);

            }

            function checkTime(i){

                if(i < 10){
                    i = "0" + i;// add zero in front of numbers < 10
                }
                return i;
            }

            // CONVERT TO 12 HOUR TIME. SET AM OR PM
            function twelve_hour_time(h){

                if(h > 12){
                    h = h - 12;
                    AM_or_PM = " PM";
                }
                return h;

            }

            startTime();

        </script>

这是我的解决方案

function getTime() {
var systemDate = new Date();
var hours = systemDate.getHours();
var minutes = systemDate.getMinutes();
var strampm;
if (hours >= 12) {
    strampm= "PM";
} else {
    strampm= "AM";
}
hours = hours % 12;
if (hours == 0) {
    hours = 12;
}
_hours = checkTimeAddZero(hours);
_minutes = checkTimeAddZero(minutes);
console.log(_hours + ":" + _minutes + " " + strampm);
}

function checkTimeAddZero(i) {
if (i < 10) {
    i = "0" + i
}
return i;
}