1. <script>
    2.         var date= new Date();
    3.           /* 年 月 日 */
    4.         console.log(date)
    5.         var year  = date.getFullYear();
    6.         console.log(year)
    7.           /* 月份从0开始,要加1 */
    8.         var  month =  date.getMonth()+1;
    9.         console.log(month)
    10.         var  data = date.getDate();
    11.         console.log(data)
    12. </script>

    返回当前时间:

    1. <script>
    2.         var d = new Date();
    3.         var hours = d.getHours();
    4.         var minutes = d.getMinutes();
    5.         var seconds = d.getSeconds();
    6.         console.log(hours)
    7.         console.log(minutes)
    8.         console.log(seconds)
    9.     </script>

    输出实时时间（秒可以变化）：

    1. <body>
    2.     <div id="app"></div>
    3.     <script>
    4.         setInterval(show,1000)
    5.         function show() {
    6.             var app = document.getElementById("app")
    7.             var d = new Date();
    8.             var hours = d.getHours();
    9.             var minutes = d.getMinutes();
    10.             var seconds = d.getSeconds();
    11.             var sum = handleNum(hours) + ":" + handleNum(minutes) + ":" + handleNum(seconds);
    12.             console.log(sum)
    13.             app.innerHTML = sum;
    14.         }
    16.         function handleNum(num) {
    17.             if (num < 10) {
    18.                 num = "0" + num;
    19.             }
    20.             return num;
    21.         }
    22.     </script>
    23. </body>

    距离活动开始时间：小时分钟秒

    1. <script>
    2.         var time = "2021-10-13 17:10:10"
    3.         /* 多个小时,多分钟,多少秒 */;
    4.         /* 1、获取当前时间的毫秒数 */
    5.         var d = new Date();
    6.         // console.log(d.getTime())
    7.         var startTime = d.getTime();
    8.         /* 2、获取活动开始时间的毫秒 */
    9.         var endTime = new Date(time).getTime();
    10.         // console.log(endTime)
    11.         /* 3、得到中间间隔的毫秒数 */
    12.         var gapTime = endTime -startTime;
    13.         var seconds = Math.floor(gapTime/1000)
    14.         console.log(seconds)
    15.         var hours = Math.floor(seconds/3600);
    16.         console.log(hours)
    17.         seconds = seconds - 3600*hours;
    18.         var minutes = Math.floor(seconds/60);
    19.         console.log(minutes)
    20.         seconds = seconds - minutes*60;
    21.         console.log(seconds)
    22.         /* var time = "2021-10-13 21:30:00"  第一个需求*/
    23.         /*  var  time ="2021-10-19 08:30:00" 还有几天几小时几分 */
    24.     </script>

    把给定的time时间（毫秒）转换为几小时几分钟几秒：

    1. <script>
    2.         var time  = 360000;
    3.         /*
    4.         66s 
    5.          */
    6.         /* 
    7.           一秒
    8.         60s  一分钟       
    9.         60*60 一小时
    10.         time/1000  秒
    11.          */
    12.         var seconds = Math.floor(time/1000);
    13.         console.log(seconds)
    14.         var hours = Math.floor(seconds/3600);
    15.         console.log(hours)
    16.         // seconds = seconds- hours*3600;
    17.         seconds = seconds%3600;
    18.         console.log(seconds)
    19.         var minutes = Math.floor(seconds/60);
    20.         console.log(minutes)
    21.         seconds = seconds- minutes*60;
    22.         console.log(seconds)
    23.     </script>
    1. <script>
    2.         var time = 306000;
    3.         /* 3000 
    4.         1m = 60s
    5.         */
    6.         var seconds = time/1000;
    7.         console.log(seconds+"秒")
    8.         var minutes = Math.floor(seconds/60);
    9.         var seconds = seconds - minutes*60;
    10.         console.log(minutes+"分")
    11.         console.log(seconds+"余下的秒")
    12.         /* 3s */
    13.     </script>
    1. <script>
    2.         var time = 306150000;
    3.         /* 3000 
    4.         1m = 60s
    5.         1h = 60*60s
    6.         */
    7.         var seconds = time/1000;
    8.         console.log(seconds+"秒")
    9.         var hours = Math.floor(seconds/3600);
    10.         console.log(hours)
    11.         var seconds = seconds%3600;
    12.         console.log(seconds)
    14.         var minutes= Math.floor(seconds/60);
    15.         console.log(minutes)
    16.         seconds = seconds%60;
    17.         console.log(seconds)
    18.         /* 3s */
    19.     </script>

    现在距离10.19还有几天+几小时+几分钟：

    1. <script>
    2.         /*  var  time ="2021-10-19 08:30:00" 还有几天几小时几分 */
    3.         var time = "2021-10-19 08:30:00"
    4.         var startTime = (new Date()).getTime();
    5.         var endTime = (new Date(time)).getTime();
    6.         var gapTime = endTime-startTime;  
    7.         var minutes = Math.floor(gapTime/(1000*60));
    8.         /* 
    9.         8201分
    10.         1h = 60m
    11.         1t = 60*24
    12.          */
    13.         // console.log(minutes)
    14.         var days =  Math.floor(minutes/(60*24));
    15.         minutes = minutes -days*(60*24)
    16.         console.log(days)
    17.         var hours = Math.floor(minutes/60);
    18.         console.log(hours)
    19.         minutes = minutes - hours*60;
    20.         console.log(minutes)       
    21.  </script>