diff --git a/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.english.md b/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.english.md
index bd0264eabf..84dc71d467 100644
--- a/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.english.md
+++ b/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.english.md
@@ -9,7 +9,11 @@ challengeType: 1
The sort method sorts the elements of an array according to the callback function.
For example:
function ascendingOrder(arr) {
return arr.sort(function(a, b) {
return a - b;
});
}
ascendingOrder([1, 5, 2, 3, 4]);
// Returns [1, 2, 3, 4, 5]
function reverseAlpha(arr) {
return arr.sort(function(a, b) {
return a === b ? 0 : a < b ? 1 : -1;
});
}
reverseAlpha(['l', 'h', 'z', 'b', 's']);
// Returns ['z', 's', 'l', 'h', 'b']
-Note: It's encouraged to provide a callback function to specify how to sort the array items. JavaScript's default sorting method is by string Unicode point value, which may return unexpected results.
+JavaScript's default sorting method is by string Unicode point value, which may return unexpected results. Therefore, it is encouraged to provide a callback function to specify how to sort the array items. When such a callback function, normally called compareFunction, is supplied, the array elements are sorted according to the return value of the compareFunction:
+If compareFunction(a,b) returns a value less than 0 for two elements a and b, then a will come before b.
+If compareFunction(a,b) returns a value greater than 0 for two elements a and b, then b will come before a.
+If compareFunction(a,b) returns a value equal to 0 for two elements a and b, then a and b will remain unchanged.
+
## Instructions