Why did this piece of code return tomorrow's date ?

It must return 2013-08-31 and not 2013-09-01 as we are August 31st.

.asp?filename=tryjsref_toisostring

function myFunction() {
  var d = new Date();
  var x = document.getElementById("demo");
  x.innerHTML = d.toISOString();
}

<p id="demo">Click the button to display the date and time as a string, using the ISO
  standard.</p>
<button onclick="myFunction()">Try it</button>

Why did this piece of code return tomorrow's date ?

It must return 2013-08-31 and not 2013-09-01 as we are August 31st.

http://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_toisostring

function myFunction() {
  var d = new Date();
  var x = document.getElementById("demo");
  x.innerHTML = d.toISOString();
}

<p id="demo">Click the button to display the date and time as a string, using the ISO
  standard.</p>
<button onclick="myFunction()">Try it</button>

• javascript
• date

• developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… – Nayuki Commented Sep 1, 2013 at 1:26
• 1 How can I take MY jour and not UTC one ? – Francois Commented Sep 1, 2013 at 1:27
• Just see this post: stackoverflow.com/questions/16084313/… – Francois Commented Sep 1, 2013 at 1:28
• stackoverflow.com/questions/18551331/fullcalendar-date-format – H.D. Commented Sep 1, 2013 at 2:49

3 Answers 3

It's in UTC.

If you want to get your local timezone you have to format the date yourself (using getYear() getMonth() etc.) or use some library like date.js that will format the date for you.

With date.js it's pretty simple:

(new Date()).format('yyyy-MM-dd')

edit

As @MattJohnson noted date.js has been abandoned, but you can use alternatives like moment.js.

use:

new Date().toLocaleDateString('pt-br').split( '/' ).reverse( ).join( '-' );

or

(function() {

    function pad(number) {
      if (number < 10) {
        return '0' + number;
      }
      return number;
    }

    Date.prototype.toISO1String = function() {
      return this.getFullYear() +
        '-' + pad(this.getMonth() + 1) +
        '-' + pad(this.getDate()) +
        'T' + pad(this.getHours()) +
        ':' + pad(this.getMinutes()) +
        ':' + pad(this.getSeconds()) +
        '.' + (this.getMilliseconds() / 1000).toFixed(3).slice(2, 5) +
        'Z';
    };

  })();

See: mozilla.org toISOString doc

I just modified it

You can simply use Luxon.

DateTime.fromJSDate(new Date(yourDateVariable)).toFormat('yyyy-MM-dd')