datetime - Adding dates in JavaScript in one line - Stack Overflow

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I'm trying to perform date manipulations using JavaScript on a single line, and I'm having problems with the year (not the month or day). I got the idea from this link. Am I missing something?

The code is as follows:

var newyear = new Date((new Date()).getYear(), (new Date()).getMonth(), (new Date()).getDate()+5).getFullYear();
document.write(newyear);

This gives me "110".

I'm not sure why? Thanks!

I'm trying to perform date manipulations using JavaScript on a single line, and I'm having problems with the year (not the month or day). I got the idea from this link. Am I missing something?

The code is as follows:

var newyear = new Date((new Date()).getYear(), (new Date()).getMonth(), (new Date()).getDate()+5).getFullYear();
document.write(newyear);

This gives me "110".

I'm not sure why? Thanks!

• javascript
• datetime
• date

Share Improve this question Follow asked Feb 25, 2010 at 21:09 RioRio 14.9k2222 gold badges7171 silver badges109109 bronze badges 4

• Why is newyear only 5 days after now? – kennytm Commented Feb 25, 2010 at 21:13
• Oddly, works in IE 7, yielding "2010". Haven't bothered to test in other browsers. – jball Commented Feb 25, 2010 at 21:15
• @jball: Yeah. IE is always the one that stands out. – kennytm Commented Feb 25, 2010 at 21:17
• A little testing shows that IE treats both getYear() and getFullYear() identically. More reasons not to use deprecated functions. – jball Commented Feb 25, 2010 at 21:22

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3 Answers 3

Sorted by: Reset to default 15

(new Date()).getYear()

You should use getFullYear() here. getYear() in JS means (year − 1900).

var newyear = new Date((new Date()).getFullYear(), (new Date()).getMonth(), (new Date()).getDate()+5).getFullYear();

Y2K bug aside, this is a simpler expression:

var newyear = new Date(new Date().setDate(new Date().getDate()+5)).getFullYear()

Date objects are relatively expensive and you can do this with a single Date object and less code if you don't assume it has to be a single expression.

var d = new Date(); d.setDate(d.getDate()+5); var newyear = d.getFullYear()

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