core/linked-list

This module provides a class to organize a double-ended two-way linked list. For convenience, the list API is similar to the regular JS Array API.

import LinkedList from 'core/linked-list';

const
  list = new LinkedList();

list.push(10, 11);

// 2
console.log(list.length);

// 11
console.log(list.pop());

API

Constructor

The LinkedList constructor can take any Iterable object whose elements will be used to populate the list.

import LinkedList from 'core/linked-list';

const
  list = new LinkedList([1, 2, 3]);

// 3
console.log(list.length);

Own API

first

Data of the first node in the list.

import LinkedList from 'core/linked-list';

const
  list = new LinkedList([1, 2, 3]);

// 1
console.log(list.first);

last

Data of the last node in the list.

import LinkedList from 'core/linked-list';

const
  list = new LinkedList([1, 2, 3]);

// 3
console.log(list.last);

clear

Clears all nodes from the list.

import LinkedList from 'core/linked-list';

const
  list = new LinkedList([1, 2, 3]);

list.clear();

console.log(list.first);  // undefined
console.log(list.last);   // undefined
console.log(list.length); // 0

reverse

Returns an iterator over the data in the list. The traversal will proceed from the last node to the first.

import LinkedList from 'core/linked-list';

const
  list = new LinkedList([1, 2, 3]);

// 3, 2, 1
console.log(...list.reverse());

Array-Like API

For convenience, the LinkedList API is similar to the regular JS Array API:

1. Adding and removing is done through the push/pop/shift/unshift methods.

   import LinkedList from 'core/linked-list';
   
   const
     list = new LinkedList();
   
   list.push(10, 11);
   list.unshift(9);
   
   // 11
   console.log(list.pop());
   
   // 9
   console.log(list.shift());
   

2. Checking if a node is in the list with a given value is done using includes.

   import LinkedList from 'core/linked-list';
   
   const
     list = new LinkedList([-0, 1, NaN, 2]);
   
   console.log(list.includes(0));   // true
   console.log(list.includes(1));   // true
   console.log(list.includes(NaN)); // true
   console.log(list.includes(12));  // false
   

3. Use the length getter to get the number of nodes in the list. The push/unshift methods also return the length of the list.

   import LinkedList from 'core/linked-list';
   
   const
     list = new LinkedList();
   
   list.push(10, 11); // 2
   list.unshift(9);   // 3
   
   // 3
   console.log(list.length);
   

4. To create a new list based on another, use slice.

   import LinkedList from 'core/linked-list';
   
   const
     list = new LinkedList([1, 2, 3]);
   
   // [3]
   console.log([...list.slice(-1)]);
   
   // [1, 2]
   console.log([...list.slice(0, -1)]);
   

5. There are 2 iterators to traverse the list: values (used by default) and reverse. Note that unlike arrays, here reverse returns an iterator, not a new linked list. However, you can pass this iterator to the constructor when creating a new list.

   import LinkedList from 'core/linked-list';
   
   const
     list = new LinkedList([1, 2, 3]);
   
   // [1, 2, 3]
   console.log([...list]);
   
   // [3, 2, 1]
   console.log([...list.reverse()]);
   
   const
     reversedList = new LinkedList([...list.reverse()]);
   
   // [3, 2, 1]
   console.log([...reversedList]);