<script>
        //1.隔行变色
        //获取所有的li元素，判断是奇数行还是偶数行
        var list = document.getElementById("list");
        var lis = list.getElementsByTagName("li");
        for (var i = 0; i < lis.length; i++) {
            var li = lis[i];
            if (i % 2 == 0) {
                //i是偶数，当前是奇数行
                li.style.backgroundColor = "pink";
            } else {
                //i是奇数，当前是偶数行
                li.style.backgroundColor = "skyblue";
            }
        }
        //2.高亮显示
        //给li注册鼠标经过和鼠标离开事件
        for (var i = 0; i < lis.length; i++) {
            var li = lis[i];
            var bg;
            //鼠标经过，高亮显示当前li
            li.onmouseover = function() {
                    bg = this.style.backgroundColor;
                    this.style.backgroundColor = "yellow";
                }
                //鼠标离开，还原li之前的颜色
            li.onmouseout = function() {
                this.style.backgroundColor = bg;
            }
        }
    </script>