How to order an array of arrays by index in javascript

Question

I'm trying to order an array of arrays by it's 2nd index, so if I have something like:

a[0][0] = #
a[0][1] = $
a[1][0] = x
a[1][1] = y
a[1][2] = z
a[2][0] = qaz
a[2][1] = qwerty

I get:

a[0][0] = #
a[1][0] = x
a[2][0] = qaz
a[0][1] = $
a[1][1] = y
a[2][1] = qwerty
a[1][2] = z

Thanks in advance!!

OK, so what have you tried? This site is not for other people to write all your code for you. — Jordan
– Jordan, Commented Apr 19, 2012 at 16:39
I know the sort function but doesn´t that sort it by value instead of by index??? — linker85
– linker85, Commented Apr 19, 2012 at 16:40
@linker85 Do you know that the sort function takes an optional argument which is a function that allows you to do custom sorting? — Ateş Göral
– Ateş Göral, Commented Apr 19, 2012 at 16:42
Are you actually trying to sort, or just loop through the arrays and output the values? — mafue
– mafue, Commented Apr 19, 2012 at 16:45

Kendall Frey · Accepted Answer · 2012-04-19 16:54:55Z

3

This will display the elements in the required order.

var a = [["#", "$"], ["x", "y", "z"], ["qaz", "qwerty"]]
var maxLen = 0;
for (var i = 0; i < a.length; i++)
{
    maxLen = Math.max(maxLen, a[i].length);
}
for (var y = 0; y < maxLen; y++)
{
    for (var x = 0; x < a.length; x++)
    {
        if (y < a[x].length)
        {
            alert(a[x][y]); // You could use document.write() etc.
        }
    }
}

You didn't say what you intend to do with the array elements, but this general idea will work for displaying or printing them in order.

answered Apr 19, 2012 at 16:54

Kendall Frey

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1 Comment

mafue Over a year ago

You can also use this technique to insert the elements into a new array that will preserve the sort order that you need.

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