jQuery---钢琴案例 （按下1-9数字键，能触发对应的mouseenter事件）

      //弹起的时候，触发mouseleave事件
      $(document).on("keyup", function (e) {
        // flag = true;
        // //获取到按下的键
        var code = e.keyCode;
        if (code >= 49 && code ) {
          //触发对应的li的mouseleave事件
          $(".nav li").eq(code - 49).mouseleave();
        }
      });

DOCTYPE html>
html lang="en">

head>
  meta charset="UTF-8">
  title>Titletitle>
  style>
    * {
      margin: 0;
      padding: 0;
      list-style: none;
    }

    .nav {
      width: 900px;
      height: 60px;
      background-color: black;
      margin: 0 auto;
    }

    .nav li {
      width: 100px;
      height: 60px;
      /*border: 1px solid yellow;*/
      float: left;
      position: relative;
      overflow: hidden;
    }

    .nav a {
      position: absolute;
      width: 100%;
      height: 100%;
      font-size: 24px;
      color: white;
      text-align: center;
      line-height: 60px;
      text-decoration: none;
      z-index: 2;
    }

    .nav span {
      position: absolute;
      width: 100%;
      height: 100%;
      background-color: yellow;
      top: 60px;
    }
  style>
  script src="../jquery-1.12.4.js">script>
  script>
    $(function () {
      //给li注册鼠标进入事件,让li下面的span top：0  播放音乐
      $(".nav li").mouseenter(function () {
        $(this).children("span").stop().animate({ top: 0 });
        //播放音乐
        var idx = $(this).index();
        $(".nav audio").get(idx).load();
        $(".nav audio").get(idx).play();
      }).mouseleave(function () {
        $(this).children("span").stop().animate({ top: 60 });
      });

      //节流阀  ：按下的时候，触发，如果没弹起，不让触发下一次
      //1. 定义一个flag
      var flag = true;

      //按下1-9这几个数字键，能触发对应的mouseenter事件
      $(document).on("keydown", function (e) {
        if (flag) {
          flag = false;
          //获取到按下的键
          var code = e.keyCode;
          if (code >= 49 && code  57) {
            //触发对应的li的mouseenter事件
            $(".nav li").eq(code - 49).mouseenter();
            // }
          }
        };
      });

      //弹起的时候，触发mouseleave事件
      $(document).on("keyup", function (e) {
        flag = true;
        //获取到按下的键
        var code = e.keyCode;
        if (code >= 49 && code  57) {
          //触发对应的li的mouseleave事件
          $(".nav li").eq(code - 49).mouseleave();
        }
      });
    });
  script>
head>

body>
  div class="nav">
    ul>
      li>
        a href="javascript:void(0);">导航1a>
        span>span>
      li>
      li>a href="javascript:void(0);">导航2a>span>span>li>
      li>a href="javascript:void(0);">导航3a>span>span>li>
      li>a href="javascript:void(0);">导航4a>span>span>li>
      li>a href="javascript:void(0);">导航5a>span>span>li>
      li>a href="javascript:void(0);">导航6a>span>span>li>
      li>a href="javascript:void(0);">导航7a>span>span>li>
      li>a href="javascript:void(0);">导航8a>span>span>li>
      li>a href="javascript:void(0);">导航9a>span>span>li>
    ul>

    div>
      audio src="mp3/1.ogg">audio>
      audio src="mp3/2.ogg">audio>
      audio src="mp3/3.ogg">audio>
      audio src="mp3/4.ogg">audio>
      audio src="mp3/5.ogg">audio>
      audio src="mp3/6.ogg">audio>
      audio src="mp3/7.ogg">audio>
      audio src="mp3/8.ogg">audio>
      audio src="mp3/9.ogg">audio>
    div>
  div>
body>

html>