simple implementation, does not handle errors

linked-list.js

/*
 * LinkedList
 * Very simple LinkedList implementation
 */

function Node(item, next) {
  this.item = item;
  this.next = next;
}

function LinkedList() {
  this.first = null;
}

LinkedList.prototype = {
  push: function(item) {
    this.first = new Node(item, this.first);
  },
  pop: function() {
    var previouslyFirst = this.first;
    this.first = previouslyFirst.next;
    return previouslyFirst.item;
  }
};

module.exports = LinkedList;

function main() {
  var assert = require('assert');
  var list = new LinkedList();
  list.push(1);
  list.push(2);
  assert(list.pop() === 2);
  list.push(3);
  assert(list.pop() === 3);
  assert(list.pop() === 1);
  console.log("Tests pass.");
}
if (require.main === module) main();