List data structure in JavaScript

list.js

let List =  function(){
  this.Store =  [];
  this.size = 0;
  this.pos = 0;
}

List.prototype.append  =  function(ele){
  this.Store[this.size++] = ele;
}

List.prototype.find =  function(ele){
  let i = 0, len = this.Store.length;
  for(i; i < len; i++){
    if(this.Store[i] == ele){
      return i;
    }
  }
  return -1;
}

List.prototype.remove  = function(ele){
  let foundAt =  this.find(ele);
  if(foundAt != -1){
    this.Store.splice(foundAt, 1);
    --this.size;
    return true;
  }
  return false
}

List.prototype.length =  function(){return this.size}

List.prototype.toString = function(){
  return this.Store.join("->");
}

List.prototype.insert =  function(ele, after){
  var afterPos = this.find(after);
  if(afterPos > -1){
    this.Store.splice(afterPos+1, 0, ele);
    ++this.size;
    return true;
  }
  return false;
}

List.prototype.clear =  function(){
  delete this.Store;
  this.Store = [];
  this.size = 0;
}

List.prototype.contains =  function(ele){
  if(this.find(ele.trim()) > -1){
    return true;
  }
  return false;
}

List.prototype.front =  function(){
  this.pos = 0;
}

List.prototype.end  =  function(){
  this.pos =  this.length() - 1;
}

List.prototype.getElement  = function(){
  return this.Store[this.pos];
}

List.prototype.prev =  function(){
  if(this.pos > 0){
    --this.pos
  }
  else{
    return this.pos;
  }
}

List.prototype.next = function(){
  if(this.pos < this.length()  - 1){
    ++this.pos;
  }
  else{
    return this.pos;
  }
}

List.prototype.currentPosition =  function(){
  return this.pos;
}

List.prototype.moveTo =  function(pos){
  if(pos >= 0 && pos < this.length()){
    this.pos = pos;
  }
}

List.prototype.incrementPosition =  function(){++this.pos}
List.prototype.decrementPosition =  function(){--this.pos}

List.prototype.iterateForward = function(){
  for(this.front(); this.currentPosition() < this.length(); this.incrementPosition()){
    console.log(this.getElement());
  }
}

List.prototype.iterateBackward = function(){
  for(this.end(); this.currentPosition() >= 0; this.decrementPosition()){
    console.log(this.getElement());
  }
}

let list  =  new List();

list.append("Khaled");
list.append("Fares");
list.insert("Mohammed", "Khaled");

list.iterateForward();
list.iterateBackward();