从 JavaScript 中的当前日期获取上个月的第一个日期

Question

Please anyone share the code to find the previous month's first date from current date in JavaScript. For example, if the current date is 25th Jan 2009, I should get 1st Dec 2008 as result.

Answer 1

Straightforward enough, with the date methods :

  var x = new Date();
  x.setDate(1);
  x.setMonth(x.getMonth()-1);

Answer 2

Simplest way would be:

var x = new Date();
x.setDate(0); // 0 will result in the last day of the previous month
x.setDate(1); // 1 will result in the first day of the month

Answer 3

Deals with updating year when moving from January to December

 var prevMonth = function(dateObj) { var tempDateObj = new Date(dateObj); if(tempDateObj.getMonth) { tempDateObj.setMonth(tempDateObj.getMonth() - 1); } else { tempDateObj.setYear(tempDateObj.getYear() - 1); tempDateObj.setMonth(12); } return tempDateObj }; var wrapper = document.getElementById('wrapper'); for(var i = 0; i < 12; i++) { var x = new Date(); var prevDate = prevMonth(x.setMonth(i)); var div = document.createElement('div'); div.textContent = "start month/year: " + i + "/" + x.getFullYear() + " --- prev month/year: " + prevDate.getMonth() + "/" + prevDate.getFullYear() + " --- locale prev date: " + prevDate.toLocaleDateString(); wrapper.appendChild(div); }

 <div id='wrapper'> </div>

Answer 4

Check this link:

http://blog.dansnetwork.com/2008/09/18/javascript-date-object-adding-and-subtracting-months/

EDIT: I have drummed up an example:

Date.prototype.SubtractMonth = function(numberOfMonths) {
var d = this;
d.setMonth(d.getMonth() - numberOfMonths);
d.setDate(1);
return d;
}

$(document).ready(function() {
    var d = new Date();
    alert(d.SubtractMonth(1));
});

Answer 5

This worked for me

var curDateMonth = new Date();
var prvDateMonth = new Date(curDateMonth.getFullYear(),curDateMonth.getMonth()-1,curDateMonth.getMonth());
console.log(curDateMonth.toLocaleString('en-US', { month: 'long' }) +' vs '+ prvDateMonth.toLocaleString('en-US', { month: 'long' }));

Answer 6

Important Note: Some of the answers using setMonth() here are wrong :

One liners for use in 2019 (using ES6 syntax; supported by all major browsers and Node):

    const date = new Date().toISOString(); // "2019-09-18T13:49:12.775Z"
    const [yyyy, mm, dd, h, i, s] = date.split(/T|:|-/);


    // previous month's last day
    const prev = new Date(new Date().setDate(0)).toISOString();
    const [pyyyy, pmm] = prev.split(/T|:|-/);

Note that Array destructuring allows you to skip parts:

    const date = new Date().toISOString();
    const [, , dd, , i] = date.split(/T|:|-/);

Explanation : The code above gets the ISO date 2019-09-18T13:49:12.775Z and splits it on : or - or T which returns an array [2019, 09, 18, 13, 49, 12] which then gets destructured .

Using setMonth() is wrong:

date = new Date("Dec 31, 2019")
date.setMonth(date.getMonth() - 1);
date; // Dec 1, 2019!

Answer 7

To get 00:00:00 am of previous month use this:

let d = new Date();
d.setDate(1);
d.setMonth(d.getMonth() - 1);
d.setHours(0,0,0,0);
const lastMonthStart = new Date(d);

Hope this helps!!

Answer 8

//  Previous Month Detail
let prevStartDate = new Date(this.date.getFullYear(), this.date.getMonth() - 1, 1);
console.log(prevStartDate);
let preEndDate = new Date(this.date.getFullYear(), this.date.getMonth() - 1 + 1, 0);
console.log(preEndDate);
//Current Month Detail
let cStartDate = new Date(this.date.getFullYear(), this.date.getMonth(), 1);
console.log(cStartDate);
let cEndDate = new Date(this.date.getFullYear(), this.date.getMonth(), 1, 0);
console.log(cEndDate);
//Next Month Detail
let nStartDate = new Date(this.date.getFullYear(), this.date.getMonth() + 1, 1);
console.log(nStartDate);
let nendDate = new Date(this.date.getFullYear(), this.date.getMonth() + 1 + 1, 0);
console.log(nendDate);

Answer 9

//just try this will work fine

let date = new Date();
let month = new Date().getMonth();
let prevMonth = date.setMonth(month - 1)
let formatPrevMonth = new Date(date.setMonth(month - 1));

console.log(formatPrevMonth)

Answer 10

Below is the code which worked for me

var currentMonth = date.getMonth()+1; Here, first we assigned the getMonth() Ftn to a variable and incremented it by 1. Then var current_date = date.getFullYear()+"/"+currentMonth+"/"+date.getDate(); document.getElementById("p3").innerHTML = "Today,s date:"+current_date;

None: None of the above techniques worked for me...

Answer 11

This can easily be achieved by creating a Date object based on the input date object and changing the date to 1, decrementing the year if it was January and decrementing the month (modulo 12). An important addition to it is to subtract the offset as well.

 function getFirstOfPreviousMonth(date) { let result = new Date(date.getFullYear() - (date.getMonth()? 0: 1), (date.getMonth() + 11) % 12, 1); return new Date(result.getTime() - result.getTimezoneOffset() * 60000); } console.log(getFirstOfPreviousMonth(new Date())); console.log(getFirstOfPreviousMonth(new Date(2009, 0, 25)));