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Nicholas C. Zakas
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Linked list implementation in JavaScript
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‎LICENSE

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Copyright (c) 2009 Nicholas C. Zakas. All rights reserved.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.

‎data-structures/linked-list.htm

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<html>
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<head>
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<title>Linked List Example</title>
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<script language="javascript" type="text/javascript" src="linked-list.js"></script>
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</head>
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<body>
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<h2>Linked List Example</h2>
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<hr />
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<p>This example shows the usage of the linked list implementation.</p>
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<script>
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//test creating the linked list
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var list = new LinkedList;
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//test the add method
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list.add("red");
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list.add("orange");
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list.add("yellow");
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list.add("green");
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list.add("blue");
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list.add("indigo");
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list.add("violet");
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//test the toString() method
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document.write("<p><b>Original List: </b><br />" + list + "</p>");
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//test the item() method
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document.write("<p><b>Value of node at position 2: </b><br />" + list.item(2) + "</p>");
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//test the remove() method
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list.remove(2);
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document.write("<p><b>After removing node at position 2: </b><br />" + list + "</p>");
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list.remove(0);
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document.write("<p><b>After removing node at position 0: </b><br />" + list + "</p>");
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//test the toArray() method
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var array = list.toArray();
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document.write("<p><b>New Array from toArray() method: </b><br />" + array + "</p>");
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//prove that the Array is actually a JavaScript Array object by sorting it
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array.sort();
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document.write("<p><b>Sorted Array from toArray() method: </b><br />" + array + "</p>");
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//try emptying the list
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while (list.size()){
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list.remove(0);
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}
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document.write("<p><b>List after removing all: </b><br />" + list + "</p>");
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</script>
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</body>
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</html>

‎data-structures/linked-list.js

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/*
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* Linked List implementation in JavaScript
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* Copyright (c) 2009 Nicholas C. Zakas
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* See LICENSE for details on license.
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*/
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//=================================================================
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// LinkedListNode Implementation
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//=================================================================
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//-----------------------------------------------------------------
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// Class LinkedListNode
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//-----------------------------------------------------------------
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// Author(s)
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// Nicholas C. Zakas (NCZ), 9/5/02
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//
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// Description
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// A linked list data node.
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//
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// Arguments
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// vData (Variant) - the data to store in the node.
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//-----------------------------------------------------------------
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function LinkedListNode(vData) {
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this.data = vData; //the data for this node
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this.next = null; //pointer to next node in the list
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}
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//=================================================================
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// LinkedList Implementation
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//=================================================================
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/**
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* A linked list implementation in JavaScript.
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* @class LinkedList
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* @constructor
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*/
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function LinkedList() {
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/**
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* The number of items in the list.
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* @property _length
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* @type int
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* @private
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*/
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this._length = 0;
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/**
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* Pointer to first item in the list.
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* @property _list
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* @type Object
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* @private
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*/
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this._list = null;
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}
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LinkedList.prototype = {
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//restore constructor
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constructor: LinkedList,
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/**
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* Appends some data to the end of the list. This method traverses
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* the existing list and places the value at the end in a new item.
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* @param {variant} data The data to add to the list.
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* @return {Void}
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* @method add
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*/
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add: function (data){
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//create a new item object, place data in
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var item = {
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data: data,
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next: null
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},
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//used to traverse the structure
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current,
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previous;
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//special case: no items in the list yet
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if (this._list === null){
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this._list = item;
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} else {
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previous = this._list;
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current = this._list.next;
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while(current){
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previous = current;
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current = current.next;
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}
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previous.next = item;
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}
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//don't forget to update the count
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this._length++;
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},
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/**
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* Retrieves the data in the given position in the list.
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* @param {int} index The zero-based index of the item whose value
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* should be returned.
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* @return {variant} The value in the "data" portion of the given item
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* or null if the item doesn't exist.
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* @method item
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*/
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item: function(index){
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//check for out-of-bounds values
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if (index > -1 && index < this._length){
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var current = this._list,
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i = 0;
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while(i++ < index){
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current = current.next;
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}
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return current.data;
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} else {
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return null;
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}
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},
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/**
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* Removes the item from the given location in the list.
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* @param {int} index The zero-based index of the item to remove.
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* @return {variant} The data in the given position in the list or null if
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* the item doesn't exist.
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* @method remove
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*/
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remove: function(index){
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//check for out-of-bounds values
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if (index > -1 && index < this._length){
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var current = this._list,
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previous,
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i = 0;
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//special case: removing first item
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if (index === 0){
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this._list = current.next;
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} else {
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//find the right location
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while(i++ < index){
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previous = current;
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current = current.next;
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}
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//skip over the item to remove
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previous.next = current.next;
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}
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//decrement the length
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this._length--;
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//return the value
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return current.data;
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} else {
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return null;
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}
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},
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/**
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* Returns the number of items in the list.
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* @return {int} The number of items in the list.
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* @method size
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*/
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size: function(){
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return this._length;
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},
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/**
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* Converts the list into an array.
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* @return {Array} An array containing all of the data in the list.
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* @method toArray
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*/
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toArray: function(){
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var result = [],
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current = this._list;
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while(current){
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result.push(current.data);
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current = current.next;
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}
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return result;
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},
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/**
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* Converts the list into a string representation.
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* @return {String} A string representation of the list.
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* @method toString
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*/
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toString: function(){
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return this.toArray().toString();
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}
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};

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