一个简短而甜蜜的实现:

// returns date object in 12hr (AM/PM) format
var formatAMPM = function formatAMPM(d) {
    var h = d.getHours();
    return (h % 12 || 12)
        + ':' + d.getMinutes().toString().padStart(2, '0')
        + ' ' + (h < 12 ? 'A' : 'P') + 'M';
};

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;
}

使用Moment.js

使用moment.js时，请在JavaScript中使用以下代码

H, HH       24 hour time
h, or hh    12 hour time (use in conjunction with a or A)

format()方法以特定格式返回日期。

moment(new Date()).format("YYYY-MM-DD HH:mm"); // 24H clock
moment(new Date()).format("YYYY-MM-DD hh:mm A"); // 12H clock (AM/PM)
moment(new Date()).format("YYYY-MM-DD hh:mm a"); // 12H clock (am/pm)

在现代浏览器中，使用Intl。DateTimeFormat和强制12小时格式选项:

    let now = new Date();

    new Intl.DateTimeFormat('default',
        {
            hour12: true,
            hour: 'numeric',
            minute: 'numeric'
        }).format(now);

    // 6:30 AM

如果您添加更多选项，使用default将尊重浏览器的默认区域，但仍将输出12小时格式。

<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>

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()));