Implemented with ES6 classes, additional functionality.

JavaScript/3-classes.js

@@ -0,0 +1,139 @@
+'use strict';
+
+class Node {
+  constructor(list, name, data) {
+    this.list = list;
+    this.data = data;
+    this.name = name;
+    this.prev = null;
+    this.next = null;
+  }
+}
+
+class LinkedList {
+
+  constructor() {
+    this.first = null;
+    this.last = null;
+    this.length = 0;
+  }
+
+  push(name, data) {
+    const node = new Node(this, name, data);
+    node.prev = this.last;
+    if (this.length === 0) {
+      this.first = node;
+    } else {
+      this.last.next = node;
+    }
+    this.last = node;
+    this.length++;
+    return node;
+  }
+
+  pop() {
+    if (this.length > 0) {
+      const node = this.last;
+      this.last = node.prev;
+      node.list = null;
+      node.prev = null;
+      node.next = null;
+      this.length--;
+      return node.data;
+    }
+
+  }
+
+  itemAtPos(pos) {
+
+    let current = this.first;
+    let counter = 0;
+
+    if (!(this.length) || pos < 0 || pos >= this.length) {
+      return false;
+    }
+
+    while (counter < pos) {
+      current = current.next;
+      ++counter;
+    }
+
+    return current;
+  }
+
+  remove(remPos) {
+    let current = this.first;
+    let position = 0;
+
+    if (this.length < 0 || remPos >= this.length) {
+      return false;
+    }
+
+    if (remPos === 0) {
+      this.first = current.next;
+      this.first.prev = null;
+      this.length--;
+      return;
+    }
+
+    while (position < remPos) {
+      current = current.next;
+      ++position;
+    }
+
+    current.prev.next = current.next;
+    current.next.prev = current.prev;
+    this.length--;
+  }
+
+  findFirst(name) {
+    let current = this.first;
+
+    while (current && current.name !== name) {
+      current = current.next;
+    }
+    return current;
+  }
+
+  findAll(name) {
+    let current = this.first;
+    const arr = [];
+
+    while (current !== null) {
+      if (current.name === name) {
+        arr.push(current);
+      }
+      current = current.next;
+    }
+    return arr;
+  }
+
+  find(name, callback) {
+    const arr = this.findAll(name);
+    let i;
+    for (i = 0; i < arr.length; ++i) {
+      callback(arr[i]);
+    }
+  }
+}
+
+
+
+
+
+
+const list1 = new LinkedList();
+list1.push('first', 1);
+list1.push('second', 2);
+list1.push('third', 3);
+list1.push('second', 5);
+
+// console.dir(list1.findFirst('first'));
+// console.dir(list1.findAll('second'));
+// list1.find('second', n => console.log(n));
+// //console.dir(list1.searchPos(-2));
+console.dir(list1.itemAtPos(1));
+
+// console.dir(list1);
+// list1.remove(0);
+// console.dir(list1);