链表:
	javaScript中通过对象来表示节点,通过节点属性的调用来实现链表

//单个节点
function Node(el) {
  this.el = el;
  this.next = null;
}

function List() { //创建链表,并初始化头节点
  this.head = new Node("head");
  
  this.find = find;
  this.findPre = findPre;
  this.insert = insert;
  this._delete = _delete;
  this.display = display;
}

//查找节点,从头节点开始查找
function find(el) {
  
  var currentNode = this.head;
  // console.log(currentNode);

  while (currentNode.el != el&&currentNode!==null) { 
    currentNode = currentNode.next;
  }

  return currentNode;

}

//查找前驱节点
function findPre(el) {
  var currentNode = this.head;
  // console.log(currentNode);

  while (currentNode.next.el != el && currentNode.next.next!== null) { //当下一个节点的下一个节点为空时,终止循环
    currentNode = currentNode.next;
  }
  

  return currentNode;
}

//插入节点
//参数:插入节点,要插入在哪个节点
function insert(el,item) {
  var newNode = new Node(el);

  var currentNode = this.find(item);
  
  if (currentNode) {
    newNode.next = currentNode.next;
    currentNode.next = newNode;
  }

}


//删除节点,从指定节点前驱节点进行删除
function _delete (item){
  var preNode = this.findPre(item);
  
  preNode.next = preNode.next.next;
  preNode.next = null;  //释放删除节点的内存
  
}

//遍历,从头节点开始遍历
function display() {
  
  let p = this.head;
  while (p.next!==null) {
    console.log(p.next.el);
    p = p.next;
  }
}

let list = new List();

list.insert('jeff', 'head');
list.insert('tom', 'jeff');
list.insert('jim', 'tom');

list.display();

list._delete('jims');
list.display();