linked-list
Small double linked list.
Contents
- What is this?
- When should I use this?
- Install
- Use
- API
- Types
- Compatibility
- Security
- Contribute
- License
What is this?
This package is a small double linked list. Items in linked lists know about their next sibling (the item after them). In double linked lists, items also know about their previous sibling (the item before them).
When should I use this?
You can use this project as a reference for how to implement a linked list but it’s also definitely possible to use it, directly or by subclassing its lists and items.
Install
This package is ESM only. In Node.js (version 12.20+, 14.14+, or 16.0+), install with npm:
npm install linked-listIn Deno with esm.sh:
import {List, Item} from 'https://esm.sh/linked-list@3'In browsers with esm.sh:
<script type="module">
import {List, Item} from 'https://esm.sh/linked-list@3?bundle'
</script>Use
import {List, Item} from 'linked-list'
var item1 = new Item()
var item2 = new Item()
var item3 = new Item()
var list = new List(item1, item2, item3)
list.head // => item1
list.head.next // => item2
list.head.next.next // => item3
list.head.next.prev // => item1
list.tail // => item3
list.tail.next // => `null`Subclassing:
import {List, Item} from 'linked-list'
class Tokens extends List {
join(delimiter) {
return this.toArray().join(delimiter)
}
}
class Token extends Item {
constructor(value) {
super()
this.value = value
}
toString() {
return this.value
}
}
var dogs = new Token('dogs')
var and = new Token('&')
var cats = new Token('cats')
var tokens = new Tokens(dogs, and, cats)
console.log(tokens.join(' ')) // => 'dogs & cats'
and.prepend(cats)
and.append(dogs)
console.log(tokens.join(' ') + '!') // => 'cats & dogs!'API
This package exports the following identifiers: List, Item.
There is no default export.
List([items…])
new List()
new List(new Item(), new Item())Create a new linked list.
List.from([items])
List.from()
List.from([])
List.from([new Item(), new Item()])Create a new this and adds the given array of items.
Ignores null or undefined values.
Throws an error when a given item has no detach, append, or prepend
methods.
List.of([items…])
List.of()
List.of(new Item(), new Item())Creates a new linked list from the given arguments.
Defers to List.from.
List#append(item)
var list = new List()
var item = new Item()
list.head === null // => true
item.list === null // => true
list.append(item)
list.head === item // => true
item.list === list // => trueAppends an item to a list.
Throws an error when the given item has no detach, append, or prepend
methods.
Returns the given item.
List#prepend(item)
var list = new List()
var item = new Item()
list.prepend(item)Prepends an item to a list.
Throws an error when the given item has no detach, append, or prepend
methods.
Returns the given item.
List#toArray()
var item1 = new Item()
var item2 = new Item()
var list = new List(item1, item2)
var array = list.toArray()
array[0] === item1 // => true
array[1] === item2 // => true
array[0].next === item2 // => true
array[1].prev === item1 // => trueReturns the items in the list in an array.
List#head
var item = new Item()
var list = new List(item)
list.head === item // => trueThe first item in a list, and null otherwise.
List#tail
var list = new List()
var item1 = new Item()
var item2 = new Item()
list.tail === null // => true
list.append(item1)
list.tail === null // => true, see note.
list.append(item2)
list.tail === item2 // => trueThe last item in a list, and null otherwise.
Note that a list with only one item has no tail, only a head.
List#size
var list = new List()
var item1 = new Item()
var item2 = new Item()
list.size === 0 // => true
list.append(item1)
list.size === 1 // => true
list.append(item2)
list.size === 2 // => trueThe number of items in the list.
Item()
var item = new Item()Creates a new linked list Item.
Item#append(item)
var item1 = new Item()
var item2 = new Item()
new List().append(item1)
item1.next === null // => true
item1.append(item2)
item1.next === item2 // => trueAdds the given item after the operated on item in a list.
Throws an error when the given item has no detach, append, or prepend
methods.
Returns false when the operated on item is not attached to a list, otherwise the
given item.
Item#prepend(item)
var item1 = new Item()
var item2 = new Item()
new List().append(item1)
item1.prev === null // => true
item1.prepend(item2)
item1.prev === item2 // => trueAdds the given item before the operated on item in a list.
Throws an error when the given item has no detach, append, or prepend
methods.
Returns false when the operated on item is not attached to a list, otherwise
the given item.
Item#detach()
var item = new Item()
var list = new List(item)
item.list === list // => true
item.detach()
item.list === null // => trueRemoves the operated on item from its parent list.
Removes references to it on its parent list, and prev and next items;
relinking them when possible.
Returns the operated on item.
Even when it was already detached.
Item#next
var item1 = new Item()
var item2 = new Item()
new List(item1)
item1.next === null // => true
item2.next === null // => true
item1.append(item2)
item1.next === item2 // => true
item1.detach()
item1.next === null // => trueThe items succeeding item, and null otherwise.
Item#prev
var item1 = new Item()
var item2 = new Item()
new List(item1)
item1.prev === null // => true
item2.prev === null // => true
item1.append(item2)
item1.prev === item2 // => true
item2.detach()
item2.prev === null // => trueThe items preceding item, and null otherwise.
Item#list
var item = new Item()
var list = new List()
item.list === null // => true
list.append(item)
item.list === list // => true
item.detach()
item.list === null // => trueThe items parent list, and null otherwise.
Types
This package is fully typed with TypeScript. There are no extra exported types.
Compatibility
This package is at least compatible with all maintained versions of Node.js. As of now, that is Node.js 12.20+, 14.14+, and 16.0+. It also works in Deno and modern browsers.
Security
This package is safe.
Contribute
Yes please! See How to Contribute to Open Source.