Listish

Basic list structures for JavaScript implemented using Maps as the underlying data storage.

Lists are superior to arrays for data where items need to be removed, inserted, concatenated, or split. They are inferior to arrays for indexed lookup and require more memory per item. They are equivalent for iteration.

Install

npm install listish

Or include in browser. Map and WeakMap are required (shim for IE9+ here).

Common properties and functions

All of the below data structures share the following:

• length Number of items contained
• toArray Create a new array containing the items in the structure
• toJSON Same as toArray
• toString Output a debuggable serialization
• inspect Fancier debug inspection

LinkedList

• current Current item
• head First item in the list
• tail Last item in the list
• prepend Insert a new item at beginning of the list
• append Insert a new item at end of the list
• shift Remove item from beginning of the list and return it
• insert Insert item directly after the current item
• remove Remove the current item and return its value
• next Move to the next item and return its value
• rewind Move to the head of the list and return its value
• concat Append a list to the end of this list, points to the same underlying data

Stack

FILO (first in, last out) data structure.

push          pop
\__\         /__/
   --> top --^   _
      |___|       |
      |___|     length
      |___|      _|

• top Top value which will be removed by pop or pushed down by push
• push Add a new value top the top of the stack
• pop Remove a value from the top of the stack and return it
• concat Append a stack to the top of this stack, points to the same underlying data

Queue

FIFO (First in, first out) data structure.

dequeue
 \___\    front
      ^--|____|____|____|
                         ^-- \___\
                            enqueue
         |-----length----|

• front Front value of the list which will be removed and returned by dequeue
• enqueue Add an item to the end of the queue
• dequeue Remove an item from the front of the queue and return it
• concat Append another queue to end of this queue, points to the same underlying data