JavaScript: how to calculate the date that is 2 days ago? [duplicate]

Question

Possible Duplicate:
Subtract days from a date in javascript

I have got a JavaScript that basically returns a date that is 2 days ago. It is as follows:

var x; var m_names = new Array("January", "February", "March",      "April", "May", "June", "July", "August", "September",      "October", "November", "December");  var d = new Date(); var twoDaysAgo = d.getDate()-2;  //change day here var curr_month = d.getMonth(); var curr_year = d.getFullYear(); var x = twoDaysAgo + "-" + m_names[curr_month] + "-" + curr_year;  document.write(x); 

Assuming today is 12-December-2012, the above will return the date 10-December-2012. I don't think this will work dynamically as we move forward into a new month, OR, change the day from -2 to -15. It will work only from the 3rd of the month.

How can I modify this so when it is 12-December-2012 today and I want it to return me the date 15 days ago it should be 27-November-2012... and not -3-December-2012?

Any help appreciated. Thanks! I'm a Javascript newbie.

Answer 1

If you have a date object, you can set it to two days previous by subtracting two from the date:

var d = new Date();  d.setDate(d.getDate() - 2);  console.log(d.toString());    // First of month  var c = new Date(2017,1,1); // 1 Feb -> 30 Jan  c.setDate(c.getDate() - 2);  console.log(c.toString());    // First of year  var b = new Date(2018,0,1); // 1 Jan -> 30 Dec  b.setDate(b.getDate() - 2);  console.log(b.toString());

Answer 2

You can do the following

​var date = new Date(); var yesterday = date - 1000 * 60 * 60 * 24 * 2;   // current date's milliseconds - 1,000 ms * 60 s * 60 mins * 24 hrs * (# of days beyond one to go back) yesterday = new Date(yesterday); console.log(yesterday);​ 

The Date is available as a number in miliiseconds, you take today subtract two days and create a new date using that number of milliseconds