function LinkedList(){
var Node = function(element){
this.element = element
this.next = null
}
var length = 0
var head = null
this.append = function(element){
var node = new Node(element)
var current
if(head == null){ //链表为空
head = node
}else{ //链表不为空
current = head
//循环链表，直到最后一项
while(current.next){
current = current.next
}
current.next = node
}
length ++ //更新链表长度
}
this.insert = function(position,element){
var node = new Node(element)
var current = head
var previous
var index = 0
if(position>=1 && position<=length){ //判断是否越界
if(position === 0){ //插入首部
node.next = current
head = node
}else{
while(index++ < position){
previous = current
current = current.next
}
node.next = current
previous.next = node
}
length ++ //更新链表长度
return true
}else{
return false
}
}
this.indexOf = function(element){
var current = head
var index = -1
while(current){
if (element === current.element) {
return index
}
index++
current = current.next
}
return -1
}
this.removeAt = function(position){
if(position>-1 && position<length){ //判断是否越界
var current = head
var previous
var index = 0
if(position === 0){ //移除第一个元素
head = current.next
}else{
while(index++ < position){
previous = current
current = current.next
}
previous.next = current.next //移除元素
}
length -- //更新长度
return current.element
}else{
return null
}
}
this.remove = function(element){
var index = this.indexOf(element)
return this.removeAt(index)
}
this.isEmpty = function(){
return length == 0
}
this.size = function(){
return length
}
this.toString = function(){
var current = head
var string = ""
while(current){
string = "," + current.element
current = current.next
}
return string.slice(1)
}
this.getHead = function(){
return head
}
}