ImmutableStack.js

class ImmutableStack {
  #head;

  constructor(node){
    this.#head = node
  }
 
  push(value){
    const node = {
      value,
      next : this.#head
    }
   
    return new ImmutableStack(node)
  }

  peak(){
    return this.#head?.value
  }

  pop(){
    const safeNode = this.#head ?? {}
  
    return new ImmutableStack(safeNode.next);
  }

  [Symbol.iterator]=function*(){
    let safeNode = this.#head ?? {}
    while(safeNode.value){
      yield safeNode.value
      safeNode = safeNode.next ?? {}
    }
  }
}

let stack = new Stack()

stack = stack.push(1)
stack = stack.push(2)
stack.peak() // 2
stack = stack.pop()
stack.peak() // 1

stack = stack.push(3)
stack = stack.push(4)
stack = stack.push(2)
stack = stack.push(2)

console.log([...stack]) // [ 2, 2, 4, 3, 1 ]