Add fromArray() methods to LinkedList and DoublyLinkedList.

Author: trekhleb

src/data-structures/doubly-linked-list/DoublyLinkedList.js

@@ -214,11 +214,12 @@ export default class DoublyLinkedList {
   }
 
   /**
-   * @param {DoublyLinkedListNode[]} array - Array of nodes
-   * @return {DoublyLinkedListNode[]}
+   * @param {*[]} values - Array of values that need to be converted to linked list.
+   * @return {DoublyLinkedList}
    */
-  fromArray(arr = []) {
-    arr.forEach(node => this.append(node.value));
+  fromArray(values) {
+    values.forEach(value => this.append(value));
+
     return this;
   }
 

src/data-structures/doubly-linked-list/__test__/DoublyLinkedList.test.js

@@ -36,21 +36,11 @@ describe('DoublyLinkedList', () => {
     expect(linkedList.toString()).toBe('3,2,1');
   });
 
-  it('should append new nodes from array', () => {
-    const linkedList1 = new DoublyLinkedList();
-    linkedList1.append(1);
-    linkedList1.append(1);
-    linkedList1.append(2);
-    linkedList1.append(3);
-    linkedList1.append(3);
-    linkedList1.append(3);
-    linkedList1.append(4);
-    linkedList1.append(5);
-    const array = linkedList1.toArray();
-
-    const linkedList2 = new DoublyLinkedList();
-    linkedList2.fromArray(array);
-    expect(linkedList2.toString()).toBe('1,1,2,3,3,3,4,5');
+  it('should create linked list from array', () => {
+    const linkedList = new DoublyLinkedList();
+    linkedList.fromArray([1, 1, 2, 3, 3, 3, 4, 5]);
+
+    expect(linkedList.toString()).toBe('1,1,2,3,3,3,4,5');
   });
 
   it('should delete node by value from linked list', () => {

src/data-structures/linked-list/LinkedList.js

@@ -175,6 +175,16 @@ export default class LinkedList {
     return deletedHead;
   }
 
+  /**
+   * @param {*[]} values - Array of values that need to be converted to linked list.
+   * @return {LinkedList}
+   */
+  fromArray(values) {
+    values.forEach(value => this.append(value));
+
+    return this;
+  }
+
   /**
    * @return {LinkedListNode[]}
    */

src/data-structures/linked-list/__test__/LinkedList.test.js

@@ -184,6 +184,13 @@ describe('LinkedList', () => {
     expect(linkedList.find({ callback: value => value.key === 'test5' })).toBeNull();
   });
 
+  it('should create linked list from array', () => {
+    const linkedList = new LinkedList();
+    linkedList.fromArray([1, 1, 2, 3, 3, 3, 4, 5]);
+
+    expect(linkedList.toString()).toBe('1,1,2,3,3,3,4,5');
+  });
+
   it('should find node by means of custom compare function', () => {
     const comparatorFunction = (a, b) => {
       if (a.customValue === b.customValue) {