improve readability in some sorting algorithms

src/algorithms/sorting/insertion-sort/InsertionSort.js

@@ -2,7 +2,7 @@ import Sort from '../Sort';
 
 export default class InsertionSort extends Sort {
   sort(originalArray) {
-    const array = originalArray.slice(0);
+    const array = [...originalArray];
 
     // Go through all array elements...
     for (let i = 0; i < array.length; i += 1) {

src/algorithms/sorting/quick-sort/QuickSort.js

@@ -3,7 +3,7 @@ import Sort from '../Sort';
 export default class QuickSort extends Sort {
   sort(originalArray) {
     // Clone original array to prevent it from modification.
-    const array = originalArray.slice(0);
+    const array = [...originalArray];
 
     // If array has less then or equal to one elements then it is already sorted.
     if (array.length <= 1) {

src/algorithms/sorting/selection-sort/SelectionSort.js

@@ -3,7 +3,7 @@ import Sort from '../Sort';
 export default class SelectionSort extends Sort {
   sort(originalArray) {
     // Clone original array to prevent its modification.
-    const array = originalArray.slice(0);
+    const array = [...originalArray];
 
     for (let i = 0; i < array.length - 1; i += 1) {
       let minIndex = i;

src/algorithms/sorting/shell-sort/ShellSort.js

@@ -3,7 +3,7 @@ import Sort from '../Sort';
 export default class ShellSort extends Sort {
   sort(originalArray) {
     // Prevent original array from mutations.
-    const array = originalArray.slice(0);
+    const array = [...originalArray];
 
     // Define a gap distance.
     let gap = Math.floor(array.length / 2);