Skip to content

Instantly share code, notes, and snippets.

@Metallix

Metallix/linkedlist.js

Last active Dec 16, 2015
Embed
What would you like to do?
A simple linked list implementation in JavaScript.
/*
LinkedList
Version: 1.0
Author: Metallix
Usage:
var list = new utils.LinkedList(); // Creates a new list
var item5 = list.push( 5 ); // Push a value to the end of the list. Returns a list item reference.
var item4 = list.unshift( 4 ); // Push a value to the front of the list. Returns a list item reference.
list.pop(); // Removes the last value from the list and returns it. ( 5 );
list.shift(); // Removes the first value from the list and returns it. ( 4 );
list.remove( item5 ); // Removes a item from the list. NOTE: You have to provide the item returned by push().
list.getFirstValue(); // Returns the value of the first list item;
list.getLastValue(); // Returns the value of the last list item;
function callback( value ) {
// ...
}
list.forEachValue( callback );
// Iterates over the list starting with the first item
// and calls the provided function with the value of the current list item as first argument.
*/
var utils = utils || {};
utils.LinkedList = function() {
var _first = null;
var _last = null;
this.push = function( value ) {
var item = {
value : value
}
if ( _last ) {
_last.next = item;
item.prev = _last;
_last = item;
}
else {
_first = _last = item;
}
return item;
}
this.pop = function() {
var value = null;
if ( _last ) {
value = _last.value;
if ( _last.prev ) {
_last = _last.prev;
_last.next = null;
}
else {
_last = null;
_first = null;
}
}
return value;
}
this.shift = function() {
var value = null;
if ( _first ) {
value = _first.value;
if ( _first.next ) {
_first = _first.next;
_first.prev = null;
}
else {
_last = null;
_first = null;
}
}
return value;
}
this.unshift = function( value ) {
var item = {
value : value
}
if ( _first ) {
_first.prev = item;
item.next = _first;
_first = item;
}
else {
_first = _last = item;
}
return item;
}
this.remove = function( item ) {
var current = _first;
while( current ) {
if ( current == item ) {
if ( current.prev ) current.prev.next = current.next;
else _first = current.next;
if ( current.next ) current.next.prev = current.prev;
else _last = current.prev;
return true;
}
current = current.next;
}
return false;
}
this.getFirstValue = function() {
return _first ? _first.value : null;
}
this.getLastValue = function() {
return _last ? _last.value : null;
}
this.forEachValue = function( callback, args ) {
var item = _first;
while( item ) {
callback( item.value, args );
item = item.next;
}
}
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.