Sort array by ISO 8601 date

Be careful, the accepted answer now advises to sort our dates lexicographically.

However, this will only work if all your strings use the 'Z' or '+00' timezone (= UTC). Date strings ending with 'Z' do satisfy ISO8601 standard, but all ISO8601 do not end with 'Z'.

Thus, to be fully ISO8601 compliant, you need to parse your strings with some Date library (e.g. Javascript Date or Moment.js), and compare these objects. For this part, you can check Scott's answer that also covers browsers incompatible with ISO8601.

My simple example with Javascript Date (works on any not-too-old browser) :

var myArray = [
    { name:'oldest', date:'2007-01-17T08:00:00Z' },
    { name:'newest', date:'2011-01-28T08:00:00+0100' },
    { name:'old',    date:'2009-11-25T08:00:00-0100' }
];

myArray.sort(function(a, b) {
    return new Date(a.date) - new Date(b.date);
});

Downside : This is slower than just comparing strings lexicographically.

More info about ISO8601 standard : here.

I'd go with this:

const myArray = new Array();

myArray[0] = { name:'oldest', date:'2007-01-17T08:00:00Z' }
myArray[1] = { name:'newest', date:'2011-01-28T08:00:00Z' }
myArray[2] = { name:'old',    date:'2009-11-25T08:00:00Z' }

function byDate (a, b) {
    if (a.date < b.date) return -1; 
    if (a.date > b.date) return 1; 
    return 0;  
}

const newArray = myArray.sort(byDate);


console.clear();
console.dir(myArray);
console.dir(newArray);

Sort Lexicographically:

As @kdbanman points out, ISO8601^{See General principles} was designed for lexicographical sort. As such the ISO8601 string representation can be sorted like any other string, and this will give the expected order.

'2007-01-17T08:00:00Z' < '2008-01-17T08:00:00Z' === true

So you would implement:

var myArray = [
    { name:'oldest', date:'2007-01-17T08:00:00Z' },
    { name:'newest', date:'2011-01-28T08:00:00Z' },
    { name:'old',    date:'2009-11-25T08:00:00Z' }
];

myArray.sort(function(a, b) {
    return (a.date < b.date) ? -1 : ((a.date > b.date) ? 1 : 0);
});

Sort using JavaScript Date:

Older versions of WebKit and Internet Explorer do not support ISO 8601 dates, so you have to make a compatible date. It is supported by FireFox, and modern WebKit though See here for more information about Date.parse support JavaScript: Which browsers support parsing of ISO-8601 Date String with Date.parse

Here is a very good article for creating a Javascript ISO 8601 compatible date, which you can then sort like regular javascript dates.

http://webcloud.se/log/JavaScript-and-ISO-8601/

Date.prototype.setISO8601 = function (string) {
    var regexp = "([0-9]{4})(-([0-9]{2})(-([0-9]{2})" +
    "(T([0-9]{2}):([0-9]{2})(:([0-9]{2})(\.([0-9]+))?)?" +
    "(Z|(([-+])([0-9]{2}):([0-9]{2})))?)?)?)?";
    var d = string.match(new RegExp(regexp));

    var offset = 0;
    var date = new Date(d[1], 0, 1);

    if (d[3]) { date.setMonth(d[3] - 1); }
    if (d[5]) { date.setDate(d[5]); }
    if (d[7]) { date.setHours(d[7]); }
    if (d[8]) { date.setMinutes(d[8]); }
    if (d[10]) { date.setSeconds(d[10]); }
    if (d[12]) { date.setMilliseconds(Number("0." + d[12]) * 1000); }
    if (d[14]) {
        offset = (Number(d[16]) * 60) + Number(d[17]);
        offset *= ((d[15] == '-') ? 1 : -1);
    }

    offset -= date.getTimezoneOffset();
    time = (Number(date) + (offset * 60 * 1000));
    this.setTime(Number(time));
}

Usage:

console.log(myArray.sort(sortByDate));  

function sortByDate( obj1, obj2 ) {
    var date1 = (new Date()).setISO8601(obj1.date);
    var date2 = (new Date()).setISO8601(obj2.date);
    return date2 > date1 ? 1 : -1;
}

Updated usage to include sorting technique credit @nbrooks

You can avoid creating of dates and by using the built–in lexicographic compare function String.prototype.localeCompare, rather than the ?: compound operator or other expressions:

var myArray = [
  {name: 'oldest', date: '2007-01-17T08:00:00Z'},
  {name: 'newest', date: '2011-01-28T08:00:00Z'},
  {name: 'old', date: '2009-11-25T08:00:00Z'}
];

// Oldest first
console.log(
  myArray.sort((a, b) => a.date.localeCompare(b.date))
);

// Newest first
console.log(
  myArray.sort((a, b) => -a.date.localeCompare(b.date))
);