list.js

//Implementing a Linked List in JS
//Example:
//var a = new List([1,2,3,4]);
//at = a.reverse();

function List (initialArray) {
  var list = this;
  list.first = null;
  if (!!initialArray) {
    initialArray.forEach(function (elem) {
      list.append(elem);
    });
  }
}

List.prototype.append = function (data) {
  var list = this;
  var node = { data:data, next:null }; 
  if (!!list.first) { 
    var item = list.first;
    while(item.next) {
      item = item.next;//move to the end of the list.
    }
    item.next = node;
  } else {
    list.first = node;
  }
}

List.prototype.toArray = function () {
  var arr = [];
  if (!!this.first) {
    var item = this.first;
    arr.push(item.data);
    while (item.next) {
      item = item.next;
      arr.push(item.data);
    }
  }
  return arr;
}
List.prototype.reverse = function () {
  return new List(this.toArray().reverse());
}