single-ll.js

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

class SinglyLinkedList{
  constructor(){
      this.head = null;
      this.tail = null;
      this.length = 0;
  }
  push(val){
      var newNode = new Node(val);
      if(!this.head){
          this.head = newNode;
          this.tail = this.head;
      } else {
          this.tail.next = newNode;
          this.tail = newNode;
      }
      this.length++;
      return this;
  }
  pop(){
      if(!this.head) return undefined;
      var current = this.head;
      var newTail = current;
      while(current.next){
          newTail = current;
          current = current.next;
      }
      this.tail = newTail;
      this.tail.next = null;
      this.length--;
      if(this.length === 0){
          this.head = null;
          this.tail = null;
      }
      return current;
  }
  shift(){
      if(!this.head) return undefined;
      var currentHead = this.head;
      this.head = currentHead.next;
      this.length--;
      if(this.length === 0){
          this.tail = null;
      }
      return currentHead;
  }
  unshift(val){
      var newNode = new Node(val);
      if(!this.head) {
          this.head = newNode;
          this.tail = this.head;
      }
      newNode.next = this.head;
      this.head = newNode;
      this.length++;
      return this;
  }
  get(index){
      if(index < 0 || index >= this.length) return null;
      var counter = 0;
      var current = this.head;
      while(counter !== index){
          current = current.next;
          counter++;
      }
      return current;
  }
  set(index, val){
      var foundNode = this.get(index);
      if(foundNode){
          foundNode.val = val;
          return true;
      }
      return false;
  }
  insert(index, val){
      if(index < 0 || index > this.length) return false;
      if(index === this.length) return !!this.push(val);
      if(index === 0) return !!this.unshift(val);
      
      var newNode = new Node(val);
      var prev = this.get(index - 1);
      var temp = prev.next;
      prev.next = newNode;
      newNode.next = temp;
      this.length++;
      return true;
  }
  remove(index){
      if(index < 0 || index >= this.length) return undefined;
      if(index === 0) return this.shift();
      if(index === this.length - 1) return this.pop();
      var previousNode = this.get(index - 1);
      var removed = previousNode.next;
      previousNode.next = removed.next;
      this.length--;
      return removed;
  }
  reverse(){
    var node = this.head;
    this.head = this.tail;
    this.tail = node;
    var next;
    var prev = null;
    for(var i = 0; i < this.length; i++){
      next = node.next;
      node.next = prev;
      prev = node;
      node = next;
    }
    return this;
  }
  print(){
      var arr = [];
      var current = this.head
      while(current){
          arr.push(current.val)
          current = current.next
      }
      console.log(arr);
  }
}

var list = new SinglyLinkedList()

list.push(100)
list.push(201)
list.push(250)
list.push(350)
list.push(999)