Why is this pop function of a (doubly) linked list not working?

Question

I am solving coding challenges. Currently a doubly linked list.

The pop function is not working, it is not removing the element, and I don't understand why.

I know that I should probably implement the solution using references to the last and first element of the list. But this post is not about finding a solution to the problem but about understanding why the current approach isn't working.

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

  push(value) {
    if (this.head === null) {
      this.head = new Node(value, null)
      return
    }

    var cur = this.head
    while (cur.next !== null) {
      cur = cur.next 
    }

    cur.next = new Node(value, cur)
    return
  }

  pop() {
    if (this.head === null) { return null }

    var cur = this.head

    while (cur.next !== null) {
      cur = cur.next
    }

    // here I am doing sth wrong, I guess.
    // the thinking is that when I set the (one) reference to the last element (cur) to null,
    // it should be removed from the list; why would it not be?
    let value = cur.value
    cur = null

    return value
  }
}

class Node {
  constructor(value, prev) {
    this.value = value;
    this.next = null;
    this.prev = prev;
  }
}

Answer 1

Since the comment that helped me to figure out the problem with my approach has been deleted I want to explain here myself.

I got mixed up into thinking that by saying cur = null I could change the value in the memory location, which would then affect all references to that location. Instead I simply changed the variable cur from holding a reference to holding the value null.

What I should have done instead is cur.prev.next = null.