js实现个链表吧

存储多个元素，最常用的数据结构是数组。但是数组有个一缺点，从数组中添加或移除项的成本很高，因为需要移动元素。链表也可以存储有序的元素集合，但是和数组不同，链表中的元素在内存中不是连续放置的。每个元素存储本身节点值和下一个元素的引用，链表的一个好处在于，添加或移除元素的时候不需要移动其他元素。

ok,开始实现我们的数据结构，骨架如下

  function LinkedList() {
    var Node = function (val) {
        this.val = val;
        this.next = null;
    }; //Node辅助类
    var length = 0;
    var head = null;
    this.append = function (ele) {}; //追加
    this.insert = function (pos, ele) {}; //插入
    this.removeAt = function (pos) {}; //移除
    this.indexOf = function (ele) {}; //查找元素
    this.isEmpty = function () {}; //是否为空
    this.size = function () {}; //链表元素个数
    this.getHead = function () {}; //链表头
    this.toString = function () {}; //转换为字符串
}

首先实现向链表尾部追加元素吧：

this.append = function (ele) {
    var node = new Node(ele),
        current;
    if (head == null) {
        head = node;
    } else {
        current = head;
        //找到最后一项
        while (current.next) {
            current = current.next;
        }
        //将最后一项的next指向 node
        current.next = node;
    }
    length++; //更新链表长度
}

继续实现链表插入

this.insert = function (pos, ele) {
    var node = new Node(ele);
    var idx = 0,
        previous,
        current = head;
    // 检查是否越界
    if (pos >= 0 && pos <= length) {
        if (pos === 0) {
            node.next = current;
            head = node;
        } else {
            while (idx < pos) {
                previous = current; //保存前一个节点的引用
                current = current.next;
                idx++;
            }
            node.next = current; //节点的next指向current
            previous.next = node; //前一个节点指向node
            length++; //更新数组长度
        }
    } else {
        return false;
    }
}

链表的移除：

this.removeAt = function (pos) {
    var current = head;
    var idx = 0,
        previous;
    //检查越界
    if (pos >= 0 && pos <= length) {
        if (pos === 0) {
            head = current.next;
        } else {
            while (idx < pos) {
                previous = current;
                current = current.next;
                idx++;
            }
            previous.next = current.next; //前一个节点指向下一个节点
        }
        length--; //更新链表长度
        return current.val;
    } else {
        return null
    }
}

其他方法就比较简单了，实现如下:

this.isEmpty = function () {
    return !length;
}
this.size = function () {
    return length;
}
this.getHead = function () {
    return head;
}
this.toString = function () {
    var str = '';
    var current = head;
    while (current) {
        str = str + ',' + current.val;
        current = current.next;
    }
    return str.slice(1);
}