JS二级菜单不同实现方法分析【4种方法】

时间：2021-05-26

本文实例讲述了JS二级菜单不同实现方法。分享给大家供大家参考，具体如下：

之前面试的时候被问到过一次，后来，在笔试的时候又遇到了，为了长点记性，就决定把这个好好写写。

第一种：

第一种是采用css来控制的；主要采用float，和position,display，hover来完成的。具体看以参看后面的源代码。

第二种：

主要采用hover,和display来实现的。

第三种：

采用的是js来控制的，mouseover，mouseout来控制显示的。当然也利用了css.

第四种：

这种也是纯css的形式，主要利用display:inline-block;和vertical-align:top;来实现的。如果不用vertical-align的话，就会导致一级菜单被二级菜单顶起来，使得上面无法对其，因此才需要设置。

每一种对应的源码如下：

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none;}.nav3 ul li a:hover{ color:red;}/********************************************************/.nav4{ width: 400px; height: 200px;}.nav4 ul li{ width:100px; display: inline-block; vertical-align: top;}.nav4 ul ul{ display: none;}.nav4 ul li:hover ul{ display: block;}.nav4 ul li a:hover{ color:red;}</style></head><body><div class="nav"> <ul> <li><a href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external 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