检查日期是否是“明天".或“后天"

问题描述

我正在寻找一种方法，该方法可以从接收日期的函数中返回"明天"和"后天" :

I'm looking for a way to get "tomorrow" and "the day after tomorrow" returned from a function that receives to dates:

当前日期:

将来的日期:

该函数应在此处返回明天".我尝试查找一些函数，但它们都返回0而不是1.

The function should return "tomorrow" here. I tried looking up some functions but they all return 0 not 1.

function days_between(date1, date2) {

    // The number of milliseconds in one day
    var ONE_DAY = 1000 * 60 * 60 * 24

    // Convert both dates to milliseconds
    var date1_ms = date1.getTime()
    var date2_ms = date2.getTime()

    // Calculate the difference in milliseconds
    var difference_ms = Math.abs(date1_ms - date2_ms)

    // Convert back to days and return
    return Math.round(difference_ms/ONE_DAY)

}

有什么想法吗?

推荐答案

首先，这是关于Javascript日期的文档对象及其原型.

First, here's the documentation on the Javascript Date object and its prototype.

那么，您如何确定某一天( date2 )是否隔一天( date1 )?好吧，在 date1 中添加一天，看看日期是否匹配:

So, how can you determine if a particular day (date2) is one day after another (date1)? Well, add one day to date1 and see if the dates match:

var date1_tomorrow = new Date(date1.getFullYear(), date1.getMonth(), date1.getDate() + 1);
if (date1_tomorrow.getFullYear() == date2.getFullYear() && date1_tomorrow.getMonth() == date2.getMonth() && date1_tomorrow.getDate() == date2.getDate()) {
    return "tomorrow"; // date2 is one day after date1.
}

如果要确定 date2 是否在 date1 之后两天，则可以使用与上述相同的逻辑，但要加上2天而不是1天:

If you want to determine if date2 is two days after date1, you can use the same logic as above but add 2 days instead of 1:

var date1_overmorrow = new Date(date1.getFullYear(), date1.getMonth(), date1.getDate() + 2);
if (date1_overmorrow.getFullYear() == date2.getFullYear() && date1_overmorrow.getMonth() == date2.getMonth() && date1_overmorrow.getDate() == date2.getDate()) {
    return "the day after tomorrow"; // date2 is two days after date1.
}

如果日期不是相隔1天或2天，那么最后一点就是以您想要的格式返回日期:

If the dates are not 1 or 2 days apart, the final bit would be to just return the date in your desired format:

return date2.toLocaleString(); // Firefox 29+, Chrome 24+, IE 11+
// OR
return date2.getFullYear() + '/' + (date2.getMonth() + 1) + '/' + date2.getDate() + ' ' + date2.getHours() + ':' + date2.getMinutes() + ':' + date2.getSeconds(); // Et al.

测试

function incrementDate(date, n) {
  return new Date(date.getFullYear(), date.getMonth(), date.getDate() + n);
}

function compareDates(date1, date2) {
  return date1.getFullYear() == date2.getFullYear() && date1.getMonth() == date2.getMonth() && date1.getDate() == date2.getDate();
}

function formatDate(date) {
  var year = date.getFullYear();
  var month = date.getMonth() + 1;
  var day = date.getDate();
  return year + '-' + (month < 10 ? '0' : '') + month + '-' + (day < 10 ? '0' : '') + day;
}

$(function() {
  var $output = $('#output');

  var comparisons = [
    {'start': new Date(2016, 6 - 1, 1), 'inc': 1, 'target': new Date(2016, 6 - 1, 2)},
    {'start': new Date(2016, 6 - 1, 30), 'inc': 1, 'target': new Date(2016, 7 - 1, 1)},
    {'start': new Date(2016, 12 - 1, 31), 'inc': 1, 'target': new Date(2017, 1 - 1, 1)}
  ];
  for (var i = 0, len = comparisons.length; i < len; i += 1) {
    var comp = comparisons[i];
    var $row = $('<tr>');

    $('<td>').text(formatDate(comp.start)).appendTo($row);
    $('<td>').text(comp.inc).appendTo($row);
    $('<td>').text(formatDate(comp.target)).appendTo($row);
    $('<td>').text(compareDates(comp.target, incrementDate(comp.start, comp.inc)) ? 'yes' : 'no').appendTo($row);

    $output.append($row);
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<table>
  <thead>
    <tr>
      <th>Start</th>
      <th>Inc</th>
      <th>Target</th>
      <th>Equal</th>
    </tr>
  </thead>
  <tbody id="output">
  </tbody>
</table>

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