Add JavaScript doubly linked list

Author: tshemsedinov

.gitignore

@@ -0,0 +1,3 @@
+node_modules
+*.log
+.DS_Store

JavaScript/1-doubly.js

@@ -0,0 +1,53 @@
+'use strict';
+
+function LinkedList() {
+  this.first = null;
+  this.last = null;
+  this.length = 0;
+}
+
+LinkedList.prototype.push = function(data) {
+  let node = new Node(this, data);
+  node.prev = this.last;
+  if (this.length === 0) this.first = node;
+  else this.last.next = node;
+  this.last = node;
+  this.length++;
+  return node;
+};
+
+LinkedList.prototype.pop = function() {
+  if (this.length > 0) {
+    let node = this.last;
+    this.last = node.prev;
+    node.list = null;
+    node.prev = null;
+    node.next = null;
+    this.length--;
+    return node.data;
+  }
+};
+
+function Node(list, data) {
+  this.list = list;
+  this.data = data;
+  this.prev = null;
+  this.next = null;
+}
+
+let list = new LinkedList();
+list.push({ name: 'first' });
+list.push({ name: 'second' });
+list.push({ name: 'third' });
+
+console.dir(list.pop());
+console.dir(list.pop());
+console.dir(list.pop());
+console.dir(list.pop());
+
+list.push({ name: 'uno' });
+list.push({ name: 'due' });
+console.dir(list.pop());
+list.push({ name: 'tre' });
+console.dir(list.pop());
+console.dir(list.pop());