Difference between integers = k

gistfile1.js

/*Question:

Given a non-negative integer k and an array a containing random integers, determine the number of instances where two integers in the array have a numerical difference of k.

    Do not assume anything about the given inputs unless it is strictly stated.

Example 1:
k = 4
a = [ 1, 1, 5, 6, 9, 16, 27]

output = 3      ( Due to 2x [1,5], and [5,9] )

Example 2:
k = 2
a = [ 1, 1, 3, 3]

output = 4      ( Due to 4x [1,3] )

CODE BELOW THE LINE, KTHX
___________________________________________________________________________
a = [3,1];
k = 2;

a = [2]
k = 0;

*/
function do (k, a) {
    var counter = 0;
    
    for (var i = 0; i < a.length; i++) {
        for (var j = i+1; j < a.length; j++) {
            if ((a[i] + k) == a[j] || (a[i] - k) == a[j]) { // Gotta make sure you check both directions
                counter++;
            }
        }
    }
}