单链表的尾插，头插，遍历，查找和插入

单链表的基本结构

function Node(val,next){
    this.val = val;
    this.next = next || null;
}

1.链表的创建

a.尾插法,就是正常的尾部顺序插入,从数组创建链表

function tailCreateList(aSrc){
    var head = new Node();
    pHead = head;
    aSrc.forEach((item) => {
        var node = new Node(item);
        pHead.next = node;
        pHead = node;
    })
    return head;
}

b.头插法,将后面的数据插入到头部，头结点后面，形成倒序的列表

function headCreateList(aSrc){
    var head = new Node();
    pHead = head;
    aSrc.forEach((item) => {
        var node = new Node(item);
        node.next = pHead.next;
        pHead.next = node;
    })
    return head;
}

2.链表的遍历

function traverse(head,fVisit){
    if(head == null){
        return;
    }
    var cur = head.next;
    while(cur){
        fVisit && fVisit(cur);
        cur = cur.next;
    }
}

3.链表的查找

function find(head,val){
    if(head == null){
        return;
    }
    var cur = head;
    while(cur && cur.val != val){
        cur = cur.next;
    }
    return cur;
}

4.链表的插入

function insert(head,val,newVal){
    if(head == null){
        return;
    }
    var cur = head;
    while(cur && cur.val != val){
        cur = cur.next;
    }
    if(cur){
        var newNode = new Node(newVal);
        newNode.next = cur.next;
        cur.next = newNode;
    }
}