I have an array, and am looking for duplicates.
duplicates = false; for(j = 0; j < zipcodeList.length; j++){ for(k = 0; k < zipcodeList.length; k++
Initialize k = j+1. You won't compare elements to themselves and you'll also not duplicate comparisons. For example, j = 0, k = 1 and k = 0, j = 1 compare the same set of elements. This would remove the k = 0, j = 1 comparison.