A simple linked list implemented in JavaScript

linkedList.js

const LinkedList = function() {
  this.head = null;
  this.tail = null;
};

LinkedList.prototype.addToTail = function(value) {
  const newTail = { value, next: null };

  if (this.tail) {
    this.tail.next = newTail;
  } else {
    this.head = newTail;
  }
  this.tail = newTail;
};

LinkedList.prototype.removeHead = function() {
  const currentHead = this.head;
  const newHead = this.head.next;
  if (newHead === null) {
    this.tail = null;
  }
  this.head = newHead;
  return currentHead ? currentHead.value : null;
};

LinkedList.prototype.contains = function(target) {
  let node = this.head;
  while (node) {
    if (node.value === target) {
      return true;
    }
    node = node.next;
  }
  return false;
};

const list = new LinkedList();
// console.assert(list.tail === null);
// console.assert(list.head === null);
// list.addToTail(4);
// list.addToTail(5);
// console.assert(list.head.value === 4);
// console.assert(list.contains(5) === true);
// console.assert(list.contains(6) === false);
// console.assert(list.removeHead() === 4);
// console.assert(list.tail.value === 5);
// console.assert(list.removeHead() === 5);
// console.assert(list.removeHead() === null);
// console.assert(list.tail === null);
// console.assert(list.head === null);
for (let i = 0; i < 250000000; i++) {
  list.addToTail(i);
}
console.log(list.contains(300000));