[javascript] How to determine one year from now in Javascript

I'm trying to get one year from now's date, and it's not working.

JS:

var now = new Date();

var oneYr = new Date();
oneYr.setYear(now.getYear() + 1);
$("#yearFromNow").append(oneYr.toString());

var oneMonth = new Date();
oneMonth.setMonth(now.getMonth() + 1);
$("#monthFromNow").append(oneMonth.toString());

Output:

one mo. = Thu Dec 22 112 15:16:01 GMT-0500 (Eastern Standard Time)

one yr. = Sun Jan 22 2012 15:16:01 GMT-0500 (Eastern Standard Time)

The year has Dec 22 112 - ?? The month is correctly displaying Jan 22 2012.

If you want to tinker with it, http://jsbin.com/alezaj/edit#javascript,html,live. This is in Chrome and Firefox.

Thanks!

Use this:

var startDate = new Date();
    startDate.setFullYear(startDate.getFullYear() - 1);

As setYear() is deprecated, correct variant is:

// plus 1 year
new Date().setFullYear(new Date().getFullYear() + 1)
// plus 1 month
new Date().setMonth(new Date().getMonth() + 1)
// plus 1 day
new Date().setDate(new Date().getDate() + 1)

All examples return Unix timestamp, if you want to get Date object - just wrap it with another new Date(...)

This will create a Date exactly one year in the future with just one line. First we get the fullYear from a new Date, increment it, set that as the year of a new Date. You might think we'd be done there, but if we stopped it would return a timestamp, not a Date object so we wrap the whole thing in a Date constructor.

new Date(new Date().setFullYear(new Date().getFullYear() + 1))

Use setFullyear as others have posted but be aware this returns a timestamp value not a date object. It is also a good candidate imho to add functionality via the prototype. This leads us to the following pattern:

Date.prototype.addYears = function(n) {
    var now = new Date();
    return new Date(now.setFullYear(now.getFullYear() + n));
};

console.log('Year from now is', new Date().addYears(1));

Using some of the answers on this page and here, I came up with my own answer as none of these answers fully solved it for me.

Here is crux of it

var startDate = "27 Apr 2017";
var numOfYears = 1;
var expireDate = new Date(startDate);
expireDate.setFullYear(expireDate.getFullYear() + numOfYears);
expireDate.setDate(expireDate.getDate() -1);

And here a a JSFiddle that has a working example: https://jsfiddle.net/wavesailor/g9a6qqq5/

In very simple way. use this code.

// define function 
function nextYearDate(date1) {
    var date2 = new Date(date1);
    var date3 = date2.setDate(date2.getDate() - 1);
    var date = new Date(date3);
    var day = date.getDate();
    var month = date.getMonth()+1;
    var year = date.getFullYear()+1;
    var newdate = year + '-' + (month < 10 ? '0' : '') + month + '-' + (day < 10 ? '0' : '') + day;
    $("#next_date").val(newdate);
}
// call function.
<input type="date" name="current_date" id="current_date" value="" onblur="nextYearDate(this.value);" />

<input type="date" name="next_date" id="next_date" value="" onblur="nextYearDate(this.value);" />

2020

It's perfect date/time library called Moment.js with this library you can simply write:

moment().subtract(1,'year')

and call any format you wish:

moment().subtract(1,'year').toDate()
moment().subtract(1,'year').toISOString()

See full documentation here: https://momentjs.com/