why array is not sorted in javascript in increasing date or decreasing date?

Question

I am trying to sort my array of objects .Objects have date property.I need to sort my array in ascending or descending dates .I try like this

https://jsfiddle.net/rxaLu

Answer 1

The function works fine if you are expecting all dates. Looking at your data there are some invalid dates like "-"

If you can't modify the data or expect a definite date always then you need to mod your function to do something like this (or handle it in some way to your liking)

function sort_by(field, reverse, primer) {

        var key = primer ?
            function (x) {
                return primer(x[field])
            } :
            function (x) {
                return x[field]
            };

        reverse = !reverse ? 1 : -1;

        return function (a, b) {
            a = new Date(key(a))=='Invalid Date'?0:new Date(key(a));
b = new Date(key(b))=='Invalid Date'?0:new Date(key(b));
            return reverse * (a-b);
        }
    }

All props to @void for his answer. I just updated since there was a duplicate question raised for this and I don't have rep to comment on the question or on @void's answer on this post

Answer 2

Your function is pretty messed up, try

function sort_by(field, reverse, primer) {

            var key = primer ?
                function (x) {
                    return primer(x[field])
                } :
                function (x) {
                    return x[field]
                };

            reverse = !reverse ? 1 : -1;

            return function (a, b) {
                a = new Date(key(a)), b = new Date(key(b));
                return reverse * (a-b);
            }
        }

You need to convert date strings to date to sort and also you need to change your return code.

Working fiddle