Fast linked list

General purpose, but clean doubly Linked List implementation for the web (3.4kB), performing decently well in benchmarks.

Please note that the length of the list is intentionally (by default) not being computed. Token#remove() has no way of mutating the length of the list, as it does not have a reference to it's parent list, only it's siblings. If you need this, use the LengthLinkedList export, that functions analog, but provides a length attribute. This is a tradeoff between performance and functionality.

Installation

 $ npm i fast-linked-list

Usage

For simple usage, the Token architecture is abstracted away.

import LinkedList from "fast-linked-list"

const ls = new LinkedList("b", "c")
const dElem = ls.push("a")
ls.toArray() // ["b", "c", "a"]

dElem.remove() // true (meaning successfully removed)
dElem.remove() // false

const dElem2 = ls.unshift(dElem.value)

for (const elem of ls) {
  console.log(elem) // "a", "b", "c"
}

ls.reverse()

const addedElems = ls.pushBulk(["x", "y", "z"])
ls.toArray() // ["c", "b", "a", "x", "y", "z"]

addedElems[1].remove()
ls.toArray() // ["c", "b", "a", "x", "z"]

ls.pop() // "z"
ls.shift() // "c"
ls.first // "b"
ls.last // "x"

ls.reverse().forEach((e) => {
  console.log(e) // "x", "a", "b"
})

const clone = new LinkedList(ls)
ls.clear()

Note that reverse() does not mutate the list, but only inverts all basic i/o functions of the list. E.g.: push() becomes unshift() and first becomes last. Hence the reverse() call performs with a time complexity of O(1).

Working with Tokens

A Token can only exsist within one LinkedList. Appending it somewhere else will remove it from the current list.

import LinkedList, { Token } from "fast-linked-list"

const ls1 = new LinkedList("ls", "1")
const ls2 = new LinkedList("ls", "2")
const token = new Token("added")

ls1.pushToken(token); ls1.toArray() // ["ls", "1", "added"]
ls2.pushToken(token); ls2.toArray() // ["ls", "2", "added"]
ls1.toArray() // ["ls", "1"]


token.insertBefore("before")
ls2.toArray() // ["ls", "1", "before", "added"] 


// Search for a value whose Token is unknown and remove it. Preferably keep a reference to the token if you plan to remove it (as this is O(n)).
ls2.forEach((val, tok) => {
  if (val === "ls") tok.remove()
})

Contribute

All feedback is appreciated. Create a pull request or write an issue.