How do I output an ISO 8601 formatted string in Ja

Question

I have a Date object. How do I render the title portion of the following snippet?

<abbr title="2010-04-02T14:12:07">A couple days ago</abbr>

I have the "relative time in words" portion from another library.

I've tried the following:

function isoDate(msSinceEpoch) {

   var d = new Date(msSinceEpoch);
   return d.getUTCFullYear() + '-' + (d.getUTCMonth() + 1) + '-' + d.getUTCDate() + 'T' +
          d.getUTCHours() + ':' + d.getUTCMinutes() + ':' + d.getUTCSeconds();

}

But that gives me:

"2010-4-2T3:19"

Answer 1

function getdatetime() {
    d = new Date();
    return (1e3-~d.getUTCMonth()*10+d.toUTCString()+1e3+d/1)
        .replace(/1(..)..*?(\d+)\D+(\d+).(\S+).*(...)/,'$3-$1-$2T$4.$5Z')
        .replace(/-(\d)T/,'-0$1T');
}

I found the basics on Stack Overflow somewhere (I believe it was part of some other Stack Exchange code golfing), and I improved it so it works on Internet Explorer 10 or earlier as well. It's ugly, but it gets the job done.

Answer 2

To extend Sean's great and concise answer with some sugar and modern syntax:

// date.js

const getMonthName = (num) => {
  const months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Oct', 'Nov', 'Dec'];
  return months[num];
};

const formatDate = (d) => {
  const date = new Date(d);
  const year = date.getFullYear();
  const month = getMonthName(date.getMonth());
  const day = ('0' + date.getDate()).slice(-2);
  const hour = ('0' + date.getHours()).slice(-2);
  const minutes = ('0' + date.getMinutes()).slice(-2);

  return `${year} ${month} ${day}, ${hour}:${minutes}`;
};

module.exports = formatDate;

Then eg.

import formatDate = require('./date');

const myDate = "2018-07-24T13:44:46.493Z"; // Actual value from wherever, eg. MongoDB date
console.log(formatDate(myDate)); // 2018 Jul 24, 13:44

Answer 3

I would just use this small extension to Date - http://blog.stevenlevithan.com/archives/date-time-format

var date = new Date(msSinceEpoch);
date.format("isoDateTime"); // 2007-06-09T17:46:21

Answer 4

There is already a function called toISOString():

var date = new Date();
date.toISOString(); //"2011-12-19T15:28:46.493Z"

If, somehow, you're on a browser that doesn't support it, I've got you covered:

if ( !Date.prototype.toISOString ) {
  ( function() {

    function pad(number) {
      var r = String(number);
      if ( r.length === 1 ) {
        r = '0' + r;
      }
      return r;
    }

    Date.prototype.toISOString = function() {
      return this.getUTCFullYear()
        + '-' + pad( this.getUTCMonth() + 1 )
        + '-' + pad( this.getUTCDate() )
        + 'T' + pad( this.getUTCHours() )
        + ':' + pad( this.getUTCMinutes() )
        + ':' + pad( this.getUTCSeconds() )
        + '.' + String( (this.getUTCMilliseconds()/1000).toFixed(3) ).slice( 2, 5 )
        + 'Z';
    };

  }() );
}

Answer 5

Shortest, but not supported by Internet Explorer 8 and earlier:

new Date().toJSON()

Answer 6

The problem with toISOString is that it gives datetime only as "Z".

ISO-8601 also defines datetime with timezone difference in hours and minutes, in the forms like 2016-07-16T19:20:30+5:30 (when timezone is ahead UTC) and 2016-07-16T19:20:30-01:00 (when timezone is behind UTC).

I don't think it is a good idea to use another plugin, moment.js for such a small task, especially when you can get it with a few lines of code.

    var timezone_offset_min = new Date().getTimezoneOffset(),
        offset_hrs = parseInt(Math.abs(timezone_offset_min/60)),
        offset_min = Math.abs(timezone_offset_min%60),
        timezone_standard;

    if(offset_hrs < 10)
        offset_hrs = '0' + offset_hrs;

    if(offset_min > 10)
        offset_min = '0' + offset_min;

    // getTimezoneOffset returns an offset which is positive if the local timezone is behind UTC and vice-versa.
    // So add an opposite sign to the offset
    // If offset is 0, it means timezone is UTC
    if(timezone_offset_min < 0)
        timezone_standard = '+' + offset_hrs + ':' + offset_min;
    else if(timezone_offset_min > 0)
        timezone_standard = '-' + offset_hrs + ':' + offset_min;
    else if(timezone_offset_min == 0)
        timezone_standard = 'Z';

    // Timezone difference in hours and minutes
    // String such as +5:30 or -6:00 or Z
    console.log(timezone_standard); 

Once you have the timezone offset in hours and minutes, you can append to a datetime string.

I wrote a blog post on it : http://usefulangle.com/post/30/javascript-get-date-time-with-offset-hours-minutes