function getDateTime() {
  var now = new Date();
  var year = now.getFullYear();
  var month = now.getMonth() + 1;
  var day = now.getDate();

  if (month.toString().length == 1) {
    month = '0' + month;
  }
  if (day.toString().length == 1) {
    day = '0' + day;
  }

  var hours = now.getHours();
  var minutes = now.getMinutes();
  var ampm = hours >= 12 ? 'pm' : 'am';
  hours = hours % 12;
  hours = hours ? hours : 12;
  minutes = minutes < 10 ? '0' + minutes : minutes;
  var timewithampm = hours + ':' + minutes + ' ' + ampm;

  var dateTime = monthNames[parseInt(month) - 1] + ' ' + day + ' ' + year + ' ' + timewithampm;
  return dateTime;
}

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>

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。

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

函数startTime() { const today = new Date(); let h = today.getHours(); let m = today.getMinutes(); let s = today.getSeconds(); Var子午线= h >= 12 ?pm: am; H = H % 12; H = H ?H: 12; M = M < 10 ?“0”+ m: m; S = S < 10 ?“0”+ s: s; var strTime = h +“:”+ m +”:“+ s + " " +子午线; . getelementbyid(的时间)。innerText = strTime; setTimeout(开始时间,1000); ｝ 开始时间(); < h1 id = '时间' > < / h1 >

试试这个

      var date = new Date();
      var hours = date.getHours();
      var minutes = date.getMinutes();
      var seconds = date.getSeconds();
      var ampm = hours >= 12 ? "pm" : "am";