或者只是简单地执行以下代码:

    <script>
        time = function() {
            var today = new Date();
            var h = today.getHours();
            var m = today.getMinutes();
            var s = today.getSeconds();
            m = checkTime(m);
            s = checkTime(s);
            document.getElementById('txt_clock').innerHTML = h + ":" + m + ":" + s;     
            var t = setTimeout(function(){time()}, 0);
        }

        time2 = function() {
            var today = new Date();
            var h = today.getHours();
            var m = today.getMinutes();
            var s = today.getSeconds();
            m = checkTime(m);
            s = checkTime(s);
            if (h>12) {
                document.getElementById('txt_clock_stan').innerHTML = h-12 + ":" + m + ":" + s;
            }               
            var t = setTimeout(function(){time2()}, 0);
        }

        time3 = function() {
            var today = new Date();
            var h = today.getHours();
            var m = today.getMinutes();
            var s = today.getSeconds();
            if (h>12) {
                document.getElementById('hour_line').style.width = h-12 + 'em'; 
            }
            document.getElementById('minute_line').style.width = m + 'em';  
            document.getElementById('second_line').style.width = s + 'em';  
            var t = setTimeout(function(){time3()}, 0);
        }

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

它将返回如下格式

09:56 AM

如果小时数小于10，则在start中添加0

这里使用的是ES6语法

const getTimeAMPMFormat = (date) => { let hours = date. gehours (); let minutes = date.getMinutes(); Const 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' 小时=小时< 10 ?'0' + hours:小时; //如果hours小于10，则在开始时添加0 分钟=分钟< 10 ?'0' + minutes: minutes; 返回小时+ ':' +分钟+ ' ' + ampm; }; console.log (getTimeAMPMFormat(新日期));// 09:59 am

<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>

这里有另一种简单有效的方法:

        var d = new Date();

        var weekday = new Array(7);
        weekday[0] = "Sunday";
        weekday[1] = "Monday";
        weekday[2] = "Tuesday";
        weekday[3] = "Wednesday";
        weekday[4] = "Thursday";
        weekday[5] = "Friday";
        weekday[6] = "Saturday";

        var month = new Array(11);
        month[0] = "January";
        month[1] = "February";
        month[2] = "March";
        month[3] = "April";
        month[4] = "May";
        month[5] = "June";
        month[6] = "July";
        month[7] = "August";
        month[8] = "September";
        month[9] = "October";
        month[10] = "November";
        month[11] = "December";

        var t = d.toLocaleTimeString().replace(/:\d+ /, ' ');

        document.write(weekday[d.getDay()] + ',' + " " + month[d.getMonth()] + " " + d.getDate() + ',' + " " + d.getFullYear() + '<br>' + d.toLocaleTimeString());

    </script></div><!-- #time -->

我发现它在这里工作得很好。

var date_format = '12'; /* FORMAT CAN BE 12 hour (12) OR 24 hour (24)*/
 
 
var d       = new Date();
var hour    = d.getHours();  /* Returns the hour (from 0-23) */
var minutes     = d.getMinutes();  /* Returns the minutes (from 0-59) */
var result  = hour;
var ext     = '';
 
if(date_format == '12'){
    if(hour > 12){
        ext = 'PM';
        hour = (hour - 12);
        result = hour;

        if(hour < 10){
            result = "0" + hour;
        }else if(hour == 12){
            hour = "00";
            ext = 'AM';
        }
    }
    else if(hour < 12){
        result = ((hour < 10) ? "0" + hour : hour);
        ext = 'AM';
    }else if(hour == 12){
        ext = 'PM';
    }
}
 
if(minutes < 10){
    minutes = "0" + minutes; 
}
 
result = result + ":" + minutes + ' ' + ext; 
 
console.log(result);

这是活塞的例子