function addMonths(date, months) {
var d = date.getDate();
date.setMonth(date.getMonth() + +months);
if (date.getDate() != d) {
date.setDate(0);
}
return date;
}
// Add 12 months to 29 Feb 2016 -> 28 Feb 2017
console.log(addMonths(new Date(2016,1,29),12).toString());
// Subtract 1 month from 1 Jan 2017 -> 1 Dec 2016
console.log(addMonths(new Date(2017,0,1),-1).toString());
// Subtract 2 months from 31 Jan 2017 -> 30 Nov 2016
console.log(addMonths(new Date(2017,0,31),-2).toString());
// Add 2 months to 31 Dec 2016 -> 28 Feb 2017
console.log(addMonths(new Date(2016,11,31),2).toString());
var x = 12; //or whatever offset
var CurrentDate = new Date();
console.log("Current date:", CurrentDate);
CurrentDate.setMonth(CurrentDate.getMonth() + x);
console.log("Date after " + x + " months:", CurrentDate);
<a href="#" onclick="calculateMshipExp()"; return false;">Calculate Expiry Date</a>
function calculateMshipExp() {
var calcval = null;
var start_date = document.getElementById("membershipssignup_date").value;
var term = document.getElementById("membershipsmonths").value; // Is text value
var set_start = start_date.split('/');
var day = set_start[0];
var month = (set_start[1] - 1); // January is 0 so August (8th month) is 7
var year = set_start[2];
var datetime = new Date(year, month, day);
var newmonth = (month + parseInt(term)); // Must convert term to integer
var newdate = datetime.setMonth(newmonth);
newdate = new Date(newdate);
//alert(newdate);
day = newdate.getDate();
month = newdate.getMonth() + 1;
year = newdate.getFullYear();
// This is British date format. See below for US.
calcval = (((day <= 9) ? "0" + day : day) + "/" + ((month <= 9) ? "0" + month : month) + "/" + year);
// mm/dd/yyyy
calcval = (((month <= 9) ? "0" + month : month) + "/" + ((day <= 9) ? "0" + day : day) + "/" + year);
// Displays the new date in a <span id="memexp">[Date]</span> // Note: Must contain a value to replace eg. [Date]
document.getElementById("memexp").firstChild.data = calcval;
// Stores the new date in a <input type="hidden" id="membershipsexpiry_date" value="" name="membershipsexpiry_date"> for submission to database table
document.getElementById("membershipsexpiry_date").value = calcval;
}
var x = 12; //or whatever offset
var CurrentDate = new Date();
//For the very rare cases like the end of a month
//eg. May 30th - 3 months will give you March instead of February
var date = CurrentDate.getDate();
CurrentDate.setDate(1);
CurrentDate.setMonth(CurrentDate.getMonth()+X);
CurrentDate.setDate(date);
// Given a number of days, return a Date object
// that many days in the future.
function getFutureDate( days ) {
// Convert 'days' to milliseconds
var millies = 1000 * 60 * 60 * 24 * days;
// Get the current date/time
var todaysDate = new Date();
// Get 'todaysDate' as Epoch Time, then add 'days' number of mSecs to it
var futureMillies = todaysDate.getTime() + millies;
// Use the Epoch time of the targeted future date to create
// a new Date object, and then return it.
return new Date( futureMillies );
}
// Use case: get a Date that's 60 days from now.
var twoMonthsOut = getFutureDate( 60 );
var startDate = new Date(...);
var endDateMoment = moment(startDate); // moment(...) can also be used to parse dates in string format
endDateMoment.add(1, 'months');
var date = new Date("01/01/2015");
var newDate = date.addMonths(3);
console.log(newDate);
//VM208:4 Wed Apr 01 2015 00:00:00 GMT+0200 (CEST)
newDate.toISOString()
//"2015-03-31T22:00:00.000Z"
/**
* @param isoDate {string} in ISO 8601 format e.g. 2015-12-31
* @param numberMonths {number} e.g. 1, 2, 3...
* @returns {string} in ISO 8601 format e.g. 2015-12-31
*/
function addMonths (isoDate, numberMonths) {
var dateObject = new Date(isoDate),
day = dateObject.getDate(); // returns day of the month number
// avoid date calculation errors
dateObject.setHours(20);
// add months and set date to last day of the correct month
dateObject.setMonth(dateObject.getMonth() + numberMonths + 1, 0);
// set day number to min of either the original one or last day of month
dateObject.setDate(Math.min(day, dateObject.getDate()));
return dateObject.toISOString().split('T')[0];
};
function addMonthsUTC (date, count) {
if (date && count) {
var m, d = (date = new Date(+date)).getUTCDate()
date.setUTCMonth(date.getUTCMonth() + count, 1)
m = date.getUTCMonth()
date.setUTCDate(d)
if (date.getUTCMonth() !== m) date.setUTCDate(0)
}
return date
}
测试:
> d = new Date('2016-01-31T00:00:00Z');
Sat Jan 30 2016 18:00:00 GMT-0600 (CST)
> d = addMonthsUTC(d, 1);
Sun Feb 28 2016 18:00:00 GMT-0600 (CST)
> d = addMonthsUTC(d, 1);
Mon Mar 28 2016 18:00:00 GMT-0600 (CST)
> d.toISOString()
"2016-03-29T00:00:00.000Z"
非utc日期更新: (by A.Hatchkins)
function addMonths (date, count) {
if (date && count) {
var m, d = (date = new Date(+date)).getDate()
date.setMonth(date.getMonth() + count, 1)
m = date.getMonth()
date.setDate(d)
if (date.getMonth() !== m) date.setDate(0)
}
return date
}
测试:
> d = new Date(2016,0,31);
Sun Jan 31 2016 00:00:00 GMT-0600 (CST)
> d = addMonths(d, 1);
Mon Feb 29 2016 00:00:00 GMT-0600 (CST)
> d = addMonths(d, 1);
Tue Mar 29 2016 00:00:00 GMT-0600 (CST)
> d.toISOString()
"2016-03-29T06:00:00.000Z"
Date.prototype.addMonths = function (m) {
var d = new Date(this);
var years = Math.floor(m / 12);
var months = m - (years * 12);
if (years) d.setFullYear(d.getFullYear() + years);
if (months) d.setMonth(d.getMonth() + months);
return d;
}
<script>
function daysInMonth(year, month)
{
return new Date(year, month + 1, 0).getDate();
}
function addMonths(date, months)
{
var target_month = date.getMonth() + months;
var year = date.getFullYear() + parseInt(target_month / 12);
var month = target_month % 12;
var day = date.getDate();
var last_day = daysInMonth(year, month);
if (day > last_day)
{
day = last_day;
}
var new_date = new Date(year, month, day);
return new_date;
}
var endDate = addMonths(startDate, months);
</script>
function addMonths(date, months) {
let newDate = new Date(date);
var day = newDate.getDate();
newDate.setMonth(newDate.getMonth() + +months);
if (newDate.getDate() != day)
newDate.setDate(0);
return newDate;
}
