Remove Elements from a Linked List by Index Solution

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function LinkedList() {
  var length = 0;
  var head = null;

  var Node = function(element){ // {1}
    this.element = element;
    this.next = null;
  };

  this.size = function(){
    return length;
  };

  this.head = function(){
    return head;
  };

  this.add = function(element){
    var node = new Node(element);
    if(head === null){
      head = node;
    } else {
      var currentNode = head;

      while(currentNode.next){
        currentNode  = currentNode.next;
      }

      currentNode.next = node;
    }

    length++;
  };

  // Only change code below this line
  this.removeAt = function(index){
    let currentNode = head;
    let previousNode = null;
    let currentIndex = 0;
    let removeItem = null;

    if(index >= length || index < 0){
      return null
    }

    // find element at index
    while(currentIndex < index){
      previousNode = currentNode;
      currentNode = currentNode.next;
      currentIndex++;
    }

    // at this point currentNode is the node to remove
    if(currentIndex == index && previousNode != null){
      previousNode.next = currentNode.next;
      removeItem = currentNode.element;
      length --
    }
    if(!previousNode){
      removeItem = head.element
      head = head.next
      length --
    }
    return removeItem;
  }

  // Only change code above this line
}



Challenge: Remove Elements from a Linked List by Index

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