Question

我一直在尝试编写一个脚本，该脚本将花费丹佛当前时间并将其输出到URL。

我能够做到这一点：http://jsfiddle.net/Chibears85/h41wu8vz/4/

JS

$(function() {
  var today = new Date();
  var ss = today.getUTCSeconds();
  var nn = today.getUTCMinutes() - 3; //3 minute delay
  var hh = today.getUTCHours() - 6; //Offset UTC by 6 hours (Mountain Time)
  var dd = today.getUTCDate();
  var mm = today.getUTCMonth() + 1; //January is 0!
  var yyyy = today.getUTCFullYear();
  if (dd < 10) {
    dd = '0' + dd
  }
  if (mm < 10) {
    mm = '0' + mm
  }
  if (hh < 10) {
    hh = '0' + hh
  }

  var today = mm + '/' + dd + '/' + yyyy + '%20' + hh + ':' + nn + ':' + ss ;
  $('img.r').each(function() {
    var url = $(this).attr('src');
    if (url.indexOf("?") >= 0) {
      $(this).attr("src", url + today);
    } else {
      $(this).attr("src", url + "?feature_date=" + today);
    }
  });
});

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script type="text/javascript" src="screen.js"></script>
<img class="r" src="https://mywebsite.com&DateTime=" width="400">

它将日期插入URL中，但是从山区时间下午6点至12点开始时间会中断（01:00:00 10/20/2018变为-5：00：00 10/20/2018而不是19:00:00 10/19/2018）和3分钟的延迟偏移使其每小时从00:00:02中断（1:01变为1：-02而不是00:59）。

我想知道如何解决UTC偏移量，以便它不减去负数，并适当地偏移日期/月份/年份。

Answer 1

这可以用纯JS解决，尽管我最初考虑使用MomentJS。一个好的解决方案是：

var today = new Date();
var todayThreeMinutesLess = new Date(today - (3  * 60000)); // to reduce 3 minutes from current time, as 60000 ms is 1 minute;
var today = todayThreeMinutesLess.toLocaleString('en-US', {timeZone: 'America/Denver', hour12: false}).replace(', ', '%20');
$('img.r').each(function() {
    var url = $(this).attr('src');
    if (url.indexOf("?") >= 0) {
      $(this).attr("src", url + today);
    } else {
      $(this).attr("src", url + "?feature_date=" + today);
      // just to prevew the url format
      $(this).attr("alt", url + "?feature_date=" + today);
    }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<img class="r" src="https://mywebsite.com&DateTime=" width="400">

Answer 2

正如我的评论中所述，您可能可以使用new Date().toLocaleString('en-US', {timeZone: 'America/Denver'})，具体取决于您的浏览器支持需求，但是您应该注意toLocaleString locales and options may not be supported in Edge and are not supported in Android webview。

要遵循您的功能以得出结论并将UTC时间转换为山区时间（山区标准时间或山区夏令时，具体取决于一年中的时间），您必须扩展功能以处理夏时制。例如（这就是Moment.js之类的库如此受欢迎的原因，可能值得考虑您的需求）：

const twoDigit = (d) => (d < 10 ? '0' : '') + d;

const getMountainTime = () => {

  let d = new Date(); // current datetime
  let year = d.getUTCFullYear(); // utc year
  let month = d.getUTCMonth(); // utc month (jan is 0)
  let date = d.getUTCDate(); // utc date
  let hour = d.getUTCHours(); // utc hours (midnight is 0)
  var minute = d.getUTCMinutes(); // utc minutes
  var second = d.getUTCSeconds(); // utc seconds
  let day = d.getUTCDay(); // utc weekday (sunday is 0)
  let offset = 6; // assume MDT to start
  let adjust = 1; // offset adjustment at DST
  let mar = (month === 2); // march boolean
  let nov = (month === 10); // november boolean
  
  // handle march and november (DST change months)
  if (mar || nov) {
    if (mar) {
      offset = 5; // assume EST to start
      adjust = -1; // DST adjustment to EDT
    }
    // handle offset shift to prior day
    if (hour - offset < 0) {
      date -= 1;
      day -= 1;
    }
    // handle date ranges when DST change may or may not have occurred yet 
    if ((mar && date > 7 && date < 15) || (nov && date < 8)) {
      // DST adjustment on or after DST sunday at 2:00am
      if (date >= date - day && hour - offset >= 2) {
        offset += adjust;
      }
    // DST adjustment for dates after DST change has already occured  
    } else if ((mar && date > 14) || (nov && date > 7)) {
      offset += adjust;
      // handle MDT to MST offset shift to prior day (not already handled above)
      if (nov && hour === 4) {
        date -= 1;
        day -= 1;
      }
    }
  // handle months without DST changes
  } else {
    // MDT to MST adjustment for MST months
    if (month < 2 || month > 10) {
      offset += adjust;
    }
    // handle offset shift to prior day
    if (hour < offset) {
      day -= 1;
    }
  }
  
  let mm = twoDigit(month + 1);
  let dd = twoDigit(date);
  let hh = twoDigit(hour);
  let mn = twoDigit(minute);
  let ss = twoDigit(second);
  return mm + '/' + dd + '/' + year + ' ' + hh + ':' + mn + ':' + ss
}

let denver = getMountainTime();

console.log(denver);

Answer 3

您也可以为此使用date-fnc库。

import { formatToTimeZone } from 'date-fns-timezone';

const value = new Date();
const pattern = 'MMM. DD, YYYY [at] H:mma [MT]';

const outputDate =  formatToTimeZone(value, pattern, { timeZone: 'MST' })

这是格式选项https://date-fns.org/v1.9.0/docs/format

的链接

这是针对日期-fnc时区https://date-fns.org/v2.0.0-alpha.27/docs/Time-Zones

JavaScript：如何将UTC日期/时间转换为山区时间？

3 个答案: