linked list implementation in javascript
please go though mocha tests for documentation
LinkedListStack:
✓ allows adding elements through array inside constructor
✓ allows adding elements
✓ allows taking out elements at top
✓ has an iterator
✓ has direct references to first and last elements
✓ iterator allows iterating over all teh elements
✓ iterator allows access to previous and next values
✓ can remove a specific element in between linkedList
✓ can remove first element of a linkedList
✓ can remove last element of a linkedList