Initial data commit

Task/Sorting-algorithms-Heapsort/JavaScript/sorting-algorithms-heapsort.js

@@ -0,0 +1,40 @@
+function heapSort(arr) {
+    heapify(arr)
+    end = arr.length - 1
+    while (end > 0) {
+        [arr[end], arr[0]] = [arr[0], arr[end]]
+        end--
+        siftDown(arr, 0, end)
+    }
+}
+
+function heapify(arr) {
+    start = Math.floor(arr.length/2) - 1
+
+    while (start >= 0) {
+        siftDown(arr, start, arr.length - 1)
+        start--
+    }
+}
+
+function siftDown(arr, startPos, endPos) {
+    let rootPos = startPos
+
+    while (rootPos * 2 + 1 <= endPos) {
+        childPos = rootPos * 2 + 1
+        if (childPos + 1 <= endPos && arr[childPos] < arr[childPos + 1]) {
+            childPos++
+        }
+        if (arr[rootPos] < arr[childPos]) {
+            [arr[rootPos], arr[childPos]] = [arr[childPos], arr[rootPos]]
+            rootPos = childPos
+        } else {
+            return
+        }
+    }
+}
+test('rosettacode', () => {
+    arr = [12, 11, 15, 10, 9, 1, 2, 3, 13, 14, 4, 5, 6, 7, 8,]
+    heapSort(arr)
+    expect(arr).toStrictEqual([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])
+})