sort outer array based on values in inner array, javascript

Array#sort (see section 15.4.4.11 of the spec, or MDC) accepts an optional function parameter which will be used to compare two entries for sorting purposes. The function should return -1 if the first argument is "less than" the second, 0 if they're equal, or 1 if the first is "greater than" the second. So:

outerArray.sort(function(a, b) {
    var valueA, valueB;

    valueA = a[1]; // Where 1 is your index, from your example
    valueB = b[1];
    if (valueA < valueB) {
        return -1;
    }
    else if (valueA > valueB) {
        return 1;
    }
    return 0;
});

(You can obviously compress that code a bit; I've kept it verbose for clarity.)

Here is a solution not needing a separate variable to contain the index

var arr = [.....]
arr.sort((function(index){
    return function(a, b){
        return (a[index] === b[index] ? 0 : (a[index] < b[index] ? -1 : 1));
    };
})(2)); // 2 is the index

This sorts on index 2

Here used to be a sort implementation that returned the result of a simple x<y comparison. This solution is disencouraged and this post is left only to preserve the ensuing discussion.