如何在javascript中从月份和年份中获取第一个日期和最后一个日期

Question

任何人都可以帮助我从月份和年份中找到第一个日期和最后一个日期。 我有 2 个参数月和年，例如月 = 10 和年 = 2021

我尝试了一些代码，但没有答案

var prevMonthLastDay = new Date(2021, 10, 0);
var thisMonthFirstDay = new Date(2021, 10, 1);
console.log(prevMonthLastDay);
console.log(thisMonthFirstDay);

上面的代码给出了以下输出：

2021-10-30T17:00:00.000Z
2021-10-31T17:00:00.000Z 

我的预期答案是第一个日期2021-10-01和最后一个日期2021-10-31

Answer 1

你可以试试这个方法

var date = new Date();
var firstDay = new Date(date.getFullYear(), date.getMonth(), 1);
var lastDay = new Date(date.getFullYear(), date.getMonth() + 1, 0);

Answer 2

你可以按照这个。

//first and last of the current month
var current_month = "April 2017";
var arrMonth = current_month.split(" ");
var first_day = new Date(arrMonth[0] + " 1 " + arrMonth[1]);

//even though I already have the values, I'm using date functions to get year and month
//because month is zero-based
var last_day = new Date(first_day.getFullYear(), first_day.getMonth() + 1, 0, 23, 59, 59);

//use moment,js to format       
var start = moment(first_day).format("YYYY-MM-DD");
var end = moment(last_day).format("YYYY-MM-DD");

答案在以下链接中： 如何获取本月的最后一天

Answer 3

尝试以下操作以获得预期的输出：

 function GetFirstAndLastDate(year, month) { var firstDayOfMonth = new Date(year, month-1, 2); var lastDayOfMonth = new Date(year, month, 1); console.log('First Day: ' + firstDayOfMonth.toISOString().substring(0, 10)); console.log('Last Day: ' + lastDayOfMonth.toISOString().substring(0, 10)); } GetFirstAndLastDate(2021, 10);

Answer 4

我对您真正想要引用变量名称的内容有些困惑，因此我将它们全部包含在内：

const currentYear = 2021;
const currentMonth = 10;

const prevMonthFirstDay = new Date(currentYear, currentMonth - 2, 1);
const prevMonthLastDay = new Date(currentYear, currentMonth - 1, 0);

const currentMonthFirstDay = new Date(currentYear, currentMonth - 1, 1);
const currentMonthLastDay = new Date(currentYear, currentMonth, 0);

const nextMonthFirstDay = new Date(currentYear, currentMonth, 1);
const nextMonthLastDay = new Date(currentYear, currentMonth + 1, 0);

console.log('prev month first day:', prevMonthFirstDay);
console.log('prev month last day:', prevMonthLastDay);
console.log('current month first day:', currentMonthFirstDay);
console.log('current month last day:', currentMonthLastDay);
console.log('next month first day:', nextMonthFirstDay);
console.log('next month last day:', nextMonthLastDay);

在我的系统上，这将给出：

prev month first day: Wed Sep 01 2021 00:00:00 GMT+0700 (Western Indonesia Time)
prev month last day: Thu Sep 30 2021 00:00:00 GMT+0700 (Western Indonesia Time)
current month first day: Fri Oct 01 2021 00:00:00 GMT+0700 (Western Indonesia Time)
current month last day: Sun Oct 31 2021 00:00:00 GMT+0700 (Western Indonesia Time)
next month first day: Mon Nov 01 2021 00:00:00 GMT+0700 (Western Indonesia Time)
next month last day: Tue Nov 30 2021 00:00:00 GMT+0700 (Western Indonesia Time)

所以现在只需要格式化：

console.log(currentMonthFirstDay.toLocaleDateString('en-GB').split('/').reverse().join('-'));

这会给你：

2021-10-01

Answer 5

你可以试试这种方式参考

var date = new Date(), y = date.getFullYear(), m = date.getMonth();
var firstDay = new Date(y, m, 1);
var lastDay = new Date(y, m + 1, 0);