javascript - 使用计算机日期并添加日期指示器

Question

我一直在尝试显示以下“在2022年1月4^日”

在 HTML 页面上使用 javascript

const monthNames = ["January", "February", "March", "April", "May", "June",
  "July", "August", "September", "October", "November", "December"
];
const d = new Date();
var dayn = d.getDay()
var dayString;
if (dayn == 1) {
  dayString = "</b><sup>st</sup>"
} else if (dayn == 3) {
  dayString = "</b><sup>rd</sup>"
} else if (dayn >= 4) {
  dayString = "</b><sup>th</sup>"
} else {
  dayString = "</b><sup>nd</sup>"
}
var dateStr = "<b>" + dayn + dayString + "</b> day of<b> " + monthNames[d.getMonth()] + "</b> in the year <b>" + d.getFullYear(); + "</b>"
document.write(dateStr);

但由于某种原因，它今天显示为第 2 次而不是第 4次

我想显示的地方，即。2022 年 3 月4^日（今天 +89 天）它没有这样做......

所以目的是在第一行显示：

“ 2022年1月4^日”

在下一行

“不迟于2022 年 3月³日”

Answer 1

你必须使用d.getDate()而不是d.getDay()

const monthNames = ["January", "February", "March", "April", "May", "June",
  "July", "August", "September", "October", "November", "December"
];
const d = new Date();
var dayn = d.getDate();
var endDate = d.setDate(dayn + 89);
var daym = new Date(endDate).getDate();

var dayString;
if (dayn == 1) {
  dayString = "</b><sup>st</sup>"
} else if (dayn == 3) {
  dayString = "</b><sup>rd</sup>"
} else if (dayn >= 4) {
  dayString = "</b><sup>th</sup>"
} else {
  dayString = "</b><sup>nd</sup>"
}

var endDayString;
if (daym == 1) {
  endDayString = "</b><sup>st</sup>"
} else if (daym == 3) {
  endDayString = "</b><sup>rd</sup>"
} else if (daym >= 4) {
  endDayString = "</b><sup>th</sup>"
} else {
  endDayString = "</b><sup>nd</sup>"
}
 
var endDateStr = "<b>" + daym + endDayString + "</b> day of<b> " + monthNames[d.getMonth()] + "</b> in the year <b>" + d.getFullYear(); + "</b>"
document.write(endDateStr);

Answer 2

const monthNames = ["January", "February", "March", "April", "May", "June",
  "July", "August", "September", "October", "November", "December"
];
const d = new Date();
var dayn = d.getDate();
var dayString;
if (dayn == 1) {
  dayString = "</b><sup>st</sup>"
} else if (dayn == 3) {
  dayString = "</b><sup>rd</sup>"
} else if (dayn >= 4) {
  dayString = "</b><sup>th</sup>"
} else {
  dayString = "</b><sup>nd</sup>"
}
var dateStr = "<b>" + dayn + dayString + "</b> day of<b> " + monthNames[d.getMonth()] + "</b> in the year <b>" + d.getFullYear(); + "</b>"
document.write(dateStr);