js实现一个单向链表

单向链表

function LinkedList () {
    function Node (node) {
      this.node = node
      this.next = null
    }
    
    let length = 0
    let head = null
    this.append = function (node) {
      var target = new Node(node)
			var current 
			if (head === null) {
        head = target
			} else {
        current = head
				while (current.next) {
          current = current.next
				}
				current.next = target
				length++
			}
    }
    this.insert = function (element, position) {
      if (position >= 0 && position < length) {
        let node = new Node(element)
				let current = head
				let previous
				let index
        if (position === 0) {
          node.next = current
					head = node
				} else {
          while (index < position) {
            previous = current
            current = current.next
						index++
					}
          previous.next = node
          node.next = current
					length++
					return true
				}
			}else {
        return false
			}
    }
    this.removeAt = function (pos) {
			if (pos > -1 && pos < length) {
			  var current = head
				var previous
				var index = 0
				if (pos === 0) {
          head = current.next
				} else {
			    while (index < pos) {
            previous = current
						current = current.next
						index++
					}
					previous.next = current.next
				}
				length--
				return current.node
			}
    }
    this.remove = function (element) {
			let index = this.indexOf(element)
			return this.removeAt(index)
    }
    this.indexOf = function (element) {
			let current = head
			let index = 0
			while (current) {
			  if (current.node === element) {
			    return index
				} 
				index++
        current = current.next
			}
			return -1
    }
    this.isEmpty = function () {
			return length === 0
    }
    this.size = function () {
			return length
    }
    this.getHead = function () {
			return head
    }
    this.toString = function () {
			var current = head
			var string = ''
			while (current) {
			  string += current.node.toString() + (current.next ? '\r\n' : "")
				current = current.next
			}
			return string
    }
    this.print = function () {
			
    }
  }

  var link = new LinkedList()
  link.append(12)
  link.append(14)
  link.append(15)
  link.append(17)
	console.log(link.indexOf(17))