使用序数后缀格式化日期

Question

我想将我的日期格式化为如下形式，例如：2019年5月2日 星期四。

我创建了以下函数：

function convertDateToString(date) {
  let monthNames = [
    "January", "February", "March",
    "April", "May", "June", "July",
    "August", "September", "October",
    "November", "December"
  ];

  let dayNames = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"]

  let dayIndex = date.getDate();
  let monthIndex = date.getMonth();
  let year = date.getFullYear();

  return dayNames[dayIndex] + ', ' + monthNames[monthIndex] + ' ' + dayIndex + ' ' + year;
}

let date = new Date()

console.log(convertDateToString(date));

// wanted format: Thursday, May 2nd 2019

但是，我不确定如何在日期后面添加序数后缀。我目前只得到完整的数字，而不是 1st、2nd 等等。

有什么建议可以添加这个内容吗？

感谢您的回复！

- Carol.Kar

Answer 1

你可以创建一个函数，它接收一个月份中的日，例如2，并返回适当的后缀，例如nd（对于1（或21或31）的情况下为st，对于3（或23）的情况下为rd，对于其他所有情况为th）。这里是最初的回答：

const getSuffix = (num) => {
  const suffixes = {
    '1': 'st',
    '21': 'st',
    '31': 'st',
    '2': 'nd',
    '22': 'nd',
    '3': 'rd',
    '23': 'rd'
  };
  return suffixes[num] || 'th';
};
function convertDateToString(date) {
  let monthNames = [
    "January", "February", "March",
    "April", "May", "June", "July",
    "August", "September", "October",
    "November", "December"
  ];

  let dayNames = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"]

  let dayIndex = date.getDate();
  let monthIndex = date.getMonth();
  let year = date.getFullYear();

  return dayNames[dayIndex] + ', ' + monthNames[monthIndex] + ' ' + dayIndex + getSuffix(dayIndex) + ' ' + year;
}

let date = new Date()

console.log(convertDateToString(date));

// wanted format: Thursday, May 2nd 2019

- CertainPerformance

Answer 2

// Takes a number and return with ordinal suffix
const ordinal = (n) => {
  const s = ['th', 'st', 'nd', 'rd'];
  const m = n % 100;
  return n + (s[(m - 20) % 10] || s[m] || s[0]);
};

// See for yourself
for (let i = 1; i < 50; i++) {
    console.log(ordinal(i));
}

- ankr

---

非常有用，适用于每月的第49天。 - Eric Ferreira

显然这只是一个部分解决方案 - 而且验证日期的责任不应该由这个函数承担。 - ankr

只是逗你玩，哈哈。这是我选择的那一个。 - undefined

Answer 3

你可以创建一个后缀数组。

function convertDateToString(date) {
  let monthNames = [
    "January", "February", "March",
    "April", "May", "June", "July",
    "August", "September", "October",
    "November", "December"
  ];
  let suffix = ['st','nd','rd',...Array(13).fill('th'),'st','nd','rd',Array(7).fill('th'),'st']
  let dayNames = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"]

  let dayIndex = date.getDate();
  let monthIndex = date.getMonth();
  let year = date.getFullYear();

  return dayNames[dayIndex] + ', ' + monthNames[monthIndex] + ' ' + dayIndex + suffix[dayIndex-1] + ' ' + year;
}

let date = new Date()

console.log(convertDateToString(date));

// wanted format: Thursday, May 2nd 2019

- Maheer Ali

Answer 4

值得注意的是，任何时候处理日期时，都应该考虑使用 Moment.js - 它是一个可以使得处理日期变得更加简单的库。

您可以按照以下方式格式化您的显示：

function convertDateToString(date) {
  return moment(date)
    .format("dddd, MMMM Do YYYY")
}

let date1 = new Date("2019-05-01T10:00:00")
let date2 = new Date("2019-05-02T10:00:00")
let date3 = new Date("2019-05-03T10:00:00")
let date4 = new Date("2019-05-04T10:00:00")

console.log(convertDateToString(date1));
console.log(convertDateToString(date2));
console.log(convertDateToString(date3));
console.log(convertDateToString(date4));

// wanted format: Thursday, May 2nd 2019

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment.min.js"></script>

如需更多格式选项，您可以查看文档。

- VLAZ