basic linked list implementation

class ListNode {
    constructor(data) {
        this.data = data
        this.next = null                
    }
}

class LinkedList {
    constructor(head = null) {
        this.head = head
    }
  clear (){
    this.head = null;
  }

  getFirst (){
      return this.head;
  }

  getLast (){
      let lastNode = this.head;
      if (lastNode) {
          while (lastNode.next) {
              lastNode = lastNode.next
          }
      }
      return lastNode
  }

  size(){
      let count = 0; 
      let node = this.head;
      while (node) {
          count++;
          node = node.next
      }
      return count;
  }

}