Question

I’m trying to sort an Array of dates from latest to oldest, and unfortunately list.sort (by default) only sorts the first number. My array looks like this:

var MyArray = ["13 Jun", "09 Jun", "25 Aug", "30 Jun", "13 Aug"];

I tried to make a function for the .sort to reference, but the whole process is somewhat confusing to me. Could anyone help me out?

Answer 1

You’ll have to parse the strings into Date() objects, which would be straightforward enough if it weren’t for IE’s poor implementation of date string parsing. Fortunately, you can use setDate() and setMonth() with consistency across browsers, both accept numbers – 1-31 for setDate(), 0-11 for setMonth(). Setting up an object map for the month names will help.

This works for me:

(function () { 
    // Set up our variables, 2 date objects and a map of month names/numbers
    var ad = new Date();
    var bd = new Date();
    var months = {
        Jan: 0,
        Feb: 1,
        Mar: 2,
        Apr: 3,
        May: 4,
        Jun: 5,
        Jul: 6, 
        Aug: 7,
        Sep: 8,
        Oct: 9,
        Nov: 10,
        Dec: 11
    };

    MyArray.sort(function (a,b) {
        // Split the text into [ date, month ]
        var as = a.split(' '),
            bs = b.split(' ');

        // Set the Date() objects to the dates of the items
        ad.setDate(as[0]);
        ad.setMonth(months[as[1]]);
        bd.setDate(bs[0]);
        bd.setMonth(months[bs[1]]);

        /* A math operation converts a Date object to a number, so 
           it's enough to just return date1 - date2 */
        return ad - bd;
    });
})();
//-> ["09 Jun", "13 Jun", "30 Jun", "13 Aug", "25 Aug"]

I’ve set up an example for you – http://jsfiddle.net/Tw6xt/