linked_list.js

class Node {
  constructor(element) {
    this.element = element;
    this.next = null;
  }
}

class LinkedList {
  constructor() {
    this._length = 0;
    this._head = null;
  }

  append(element) {
    let node = new Node(element);
    let current;
    if (this._head === null) {
      this._head = node;
    } else {
      current = this._head;
      while (current.next) {
        current = current.next;
      }
      current.next = node;
    }
    this._length++;
  }

  insert(position, element) {
    let node = new Node(element);
    if (position > -1 && position <= this._length) {
      let current = this._head, index = 0, previous;
      if (position === 0) {
        node.next = current;
        this._head = node;
      } else {
        while (index < position) {
          previous = current;
          current = current.next;
          index++;
        }
        previous.next = node;
        node.next = current;
      }
      this._length++;
      return true;
    } else {
      return false;
    }
  }

  remove(element) {
    let index = this.indexOf(element);
    return this.removeAt(index);
  }

  removeAt(position) {
    if (position > -1 && position < this._length) {
      let current = this._head, index = 0, previous;
      if (position === 0) {
        this._head = current.next;
      } else {
        while (index < position) {
          previous = current;
          current = current.next;
          index++;
        }
        previous.next = current.next;
      }
      this._length--;
      return current.element;
    } else {
      return null;
    }
  }

  indexOf(element) {
    let current = this._head, index = 0;
    while (current) {
      if (current.element === element) {
        return index;
      }
      index++;
      current = current.next;
    }
    return -1;
  }

  isEmpty() {
    return this._length === 0;
  }

  get size() {
    return this._length;
  }

  getHead() {
    return this._head;
  }

  print() {

  }

  toString() {
    let str = '', current = this._head;
    while (current) {
      str += current.element;
      current = current.next;
    }
    return str;
  }
}