sort not working with integers?

Question

Trying to get the highest and lowest value from a array that I know will contain only integers seems to be harder than I thought?

var numArray = [140000, 104, 99];
numArray = numArray.sort();
alert(numArray[0] + ", " + numArray[numArray.length - 1]);

I'd expect this to show "99, 140000". Instead it shows "104, 99". So it seems the sort is handling the values as strings?

Any way to get the sort function to actually sort on integer value?

Answer 1

By default the sort method sorts elements alphabetically. To sort numerically just add a new method which handles numeric sorts (sortNumber, shown below) -

function sortNumber(a,b) {
    return a - b;
}

var numArray = [140000, 104, 99];
numArray = numArray.sort(sortNumber);
alert(numArray[0] + ", " + numArray[numArray.length - 1]);

Answer 2

You can pass into .sort() a function that tells it how to sort it. Here's a tutorial on this.

Answer 3

array.sort does a lexicographic sort by default, for a numeric sort, provide your own function. Here's a simple example:

function compareNumbers(a, b)
{
    return a - b;
}

numArray.sort(compareNumbers);

Also note that sort works "in place", there's no need for the assignment.

Answer 4

In Javascript the sort() method's default behaviour is to sort values in an array alphabetically.

To sort by number you have to define a numeric sort function (which is very easy):

...
function sortNumber(a,b)
{
  return a - b;
}

numArray = numArray.sort(sortNumber);