Stack in JavaScript

Stack.js

class Stack {
  constructor(){
    this.length = 0;
    this.head = null;
  }
  
   //Push data in the stack
   push = (el) => {
    //Create a new node
    let node = new Node(el),
    current;
    
    //Add the new node at the top
    current = this.head;
    node.next = current;
    this.head = node;
    
    this.length++;
  }
   
   //Pop the item from the stack
   pop = () => {
    let current = this.head;
    
    //If there is item then remove it 
    //and make the next element as the first
    if(current){
      let el = current.element;
      current = current.next;
      this.head = current;
      this.length--;
      return el;
    }
    
    return null;   
  }
  
  //Return the first element in the stack
  peek = () => {   
    if(this.head){    
      return this.head.element;
    }

    return null; 
  }
  
  //Convert the stack to an array
  toArray = () => {
    let arr = [];
    let current = this.head;
    while(current){
      arr.push(current.element);
      current = current.next;
    }
    
    return arr;
  }
  
  //Check if stack is empty
  isEmpty = () => {
    return this.length === 0;
  }
  
  //Return the size of the stack
  size = () => {
    return this.length;
  }
  
  //Clear the stack
  clear = () => {
    this.head = null;
    this.length = 0;
  }
}