var d = new Date(); var hours = d.getHours() % 12; hours = hours ? hours : 12; var test = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'][(d.getMonth() + 1)] + " " + ("00" + d.getDate()).slice(-2) + " " + d.getFullYear() + " " + ("00" + hours).slice(-2) + ":" + ("00" + d.getMinutes()).slice(-2) + ":" + ("00" + d.getSeconds()).slice(-2) + ' ' + (d.getHours() >= 12 ? 'PM' : 'AM'); document.getElementById("demo").innerHTML = test; <p id="demo" ></p>

<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>

查看Datejs。它们的内置格式化程序可以做到这一点:http://code.google.com/p/datejs/wiki/APIDocumentation#toString

这是一个非常方便的库，特别是如果您打算用date对象做其他事情时。

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

function formatTime( d = new Date(), ampm = true ) { var hour = d.getHours(); if ( ampm ) { var a = ( hour >= 12 ) ? 'PM' : 'AM'; hour = hour % 12; hour = hour ? hour : 12; // the hour '0' should be '12' } var hour = checkDigit(hour); var minute = checkDigit(d.getMinutes()); var second = checkDigit(d.getSeconds()); // https://stackoverflow.com/questions/1408289/how-can-i-do-string-interpolation-in-javascript return ( ampm ) ? `${hour}:${minute}:${second} ${a}` : `${hour}:${minute}:${second}`; } function checkDigit(t) { return ( t < 10 ) ? `0${t}` : t; } document.querySelector("#time1").innerHTML = formatTime(); document.querySelector("#time2").innerHTML = formatTime( new Date(), false ); <p>ampm true: <span id="time1"></span> (default)</p> <p>ampm false: <span id="time2"></span></p>

希望这个答案比其他答案更容易理解(尤其是对新手来说)。

以下是我在一些站点中实现的解决方案，用于通知上次修改站点代码的时间。它通过date的选项参数实现AM/PM时间。toLocaleDateString(参见相关的Mozilla文档)。

// Last time page code was updated/changed
const options = {
    year: "numeric",
    month: "long",
    weekday: "long",
    day: "numeric",
    hour: "numeric",
    minute: "numeric",
    second: "numeric",
    hour12: true // This is the line of code we care about here
    /*
        false: displays 24hs format for time
        true: displays 12, AM and PM format
    */
};

let last = document.lastModified;
let date = new Date(last);
let local = date.toLocaleDateString("en-US", options);
let fullDate = `${local}`;
document.getElementById("updated").textContent = fullDate;

输出的格式是:

Saturday, May 28, 2022, 8:38:50 PM

该输出然后显示在以下HTML代码中:

<p>Last update: <span id="updated">_update_date_goes_here</span></p>

注意:在这个用例中，是文档。lastModified有一些奇怪的行为，这取决于它是在本地运行还是在外部服务器上运行(参见这个堆栈溢出问题)。虽然当我在我的GitHub页面上运行它时，它可以正常工作(你应该在网站的页脚处看到它在运行)。