How to sort an array of dates stringified in YYYY-M format?

Question

I have an array containing strings which look like this:

["2013-1", "2013-10", "2013-11", "2013-12", "2013-2", "2013-3", "2013-4", "2014-1", "2014-2", "2014-3"]

I'm trying to sort them like so they look like:

["2013-1", "2013-2", "2013-3", "2013-4", "2013-10", "2013-11", "2013-12", "2014-1", "2014-2", "2014-3"]

I've checked out a bunch of threads on this topic but none of the solutions have worked for me.

Using this question's answer my array didn't change at all.

var myArray =  ["2013-1", "2013-10", "2013-11", "2013-12", "2013-2", "2013-3", "2013-4", "2014-1", "2014-2", "2014-3"]
    myArray.sort(function(a,b) {
      if (isNaN(a) || isNaN(b)) {
        return a > b ? 1 : -1;
      }
      return a - b;
    });

Can't seem to find a way of doing easily doing this, any ideas of how to achieve it?

Guffa · Accepted Answer · 2014-12-09 11:41:17Z

2

The problem is that it's not just numbers in a string array, there are two numbers in each string. There are many possible approchaes, you could parse the values to dates, you could parse the values to two numbers, you could split the values to a string and a number, et.c.

The approach that I suggest is to turn each string into a format that is sortable for the comparison, i.e. converting a string like "2013-1" into 2013-01. As each component in the string then has the same length, and the components are in falling importance, you can compare them as strings:

myArray.sort(function(a,b) {
  var x = a.replace(/(-\d$)/, '-0$1');
  var y = b.replace(/(-\d$)/, '-0$1');
  return (
    x > y ? 1 :
    x < y ? -1 :
    0
  );
});

var myArray = ["2013-1", "2013-10", "2013-11", "2013-12", "2013-2", "2013-3", "2013-4", "2014-1", "2014-2", "2014-3"];

myArray.sort(function(a,b) {
  var x = a.replace(/(-\d$)/, '-0$1');
  var y = b.replace(/(-\d$)/, '-0$1');
  return (
    x > y ? 1 :
    x < y ? -1 :
    0
  );
});

// output result in StackOverflow snippet
document.write(JSON.stringify(myArray));

edited Dec 9, 2014 at 11:41

answered Dec 9, 2014 at 11:20

Guffa

703k112 gold badges760 silver badges1k bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Pavlo Over a year ago

It would be simpler if you've used x.localeCompare(y) in return.

codingrose · Accepted Answer · 2014-12-09 11:30:27Z

1

One of the ways to do so:

myArray.sort(function (a, b) {
    a = a.split("-");
    b = b.split("-");
    var montha = parseInt(a[1]),
        monthb = parseInt(b[1]);
    a = parseInt(a[0]);
    b = parseInt(b[0]);
    if (a === b) {
        return (montha - monthb);
    }
    return a - b;
});

See DEMO here.

answered Dec 9, 2014 at 11:30

codingrose

15.7k11 gold badges41 silver badges58 bronze badges

Comments

Pavlo · Accepted Answer · 2014-12-09 11:58:36Z

1

Here is a functional programming approach: map strings to array of two numbers, sort that array (much easier), then map back to strings.

var input = ["2013-1", "2013-10", "2013-11", "2013-12", "2013-2", "2013-3", "2013-4", "2014-1", "2014-2", "2014-3"];
var output = input
  .map(function (val) {
    return val.split("-").map(Number);
  })
  .sort(function (a, b) {
    return a[0] - b[0] || a[1] - b[1];
  })
  .map(function (val) {
    return val.join("-");
  });

Demo: http://jsbin.com/fekiruzose/2/edit?js,console

edited Dec 9, 2014 at 11:58

answered Dec 9, 2014 at 11:38

Pavlo

45.2k14 gold badges84 silver badges114 bronze badges

Collectives™ on Stack Overflow

How to sort an array of dates stringified in YYYY-M format?

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related