使用 JavaScript 和 CSS 定位子菜单

Posted 2023-05-09

【中文标题】使用 JavaScript 和 CSS 定位子菜单

【英文标题】：Positioning submenu with JavaScript and CSS

【发布时间】：2020-12-29 12:43:57

【问题描述】：

我怎样才能使这些框具有响应性？例如，最后一个子菜单超出边界。我不知道如何验证盒子在空间上是否可见以及如何正确移动它们。在这种情况下，我想看看如何在不可见的情况下移动第二级，或者在第二级和第三级都可见但第三级不可见时移动它们。

document.addEventListener('click', function(e) 
    e = e || window.event;
    console.log(e);
    var target = e.target || e.srcElement;
    console.log(target);
    if (target.parentElement.className.indexOf('has-submenu') > -1) 
        e.target.classList.toggle('open');
    
, false);

#menu 
background: #343434;
color: #eee;
height: 35px;
border-bottom: 4px solid #eeeded


#menu ul,
#menu li 
margin: 0 0;
padding: 0 0;
list-style: none


#menu ul 
height: 35px


#menu li 
float: left;
display: inline;
position: relative;
font: bold 12px Arial;
text-shadow: 0 -1px 0 #000;
border-right: 1px solid #444;
border-left: 1px solid #111;
text-transform: uppercase


#menu li:first-child 
border-left: none


#menu a 
display: block;
line-height: 35px;
padding: 0 14px;
text-decoration: none;
color: #eee;


#menu li:hover > a,
#menu li a:hover 
background: #111


#menu input 
display: none;
margin: 0 0;
padding: 0 0;
width: 80px;
height: 35px;
opacity: 0;
cursor: pointer


#menu label 
font: bold 30px Arial;
display: none;
width: 35px;
height: 36px;
line-height: 36px;
text-align: center


#menu label span 
font-size: 12px;
position: absolute;
left: 35px


#menu ul.menus 
height: auto;
width: 180px;
background: #111;
position: absolute;
z-index: 99;
display: none;
border: 0;


#menu ul.menus li 
display: block;
width: 100%;
font: 12px Arial;
text-transform: none;


#menu li:hover ul.menus 
display: block


#menu a.home 
background: #c00;


#menu a.prett 
padding: 0 27px 0 14px


#menu a.prett::after 
content: "";
width: 0;
height: 0;
border-width: 6px 5px;
border-style: solid;
border-color: #eee transparent transparent transparent;
position: absolute;
top: 15px;
right: 9px


#menu a.prett.open::after 
content: "";
width: 0;
height: 0;
border-width: 6px 5px;
border-style: solid;
border-color: transparent transparent #eee transparent;
position: absolute;
top: 9px;
right: 9px


#menu ul.menus a:hover 
background: #333;


#menu ul.menus .submenu 
display: none;
position: absolute;
left: 180px;
background: #111;
top: 0;
width: 180px;


#menu ul.menus .submenu li 
background: #111;


#menu ul.menus .has-submenu a.open ~ .submenu 
display: block;

<nav>
  <ul id='menu'>
  <li><a class='home' href='/'>Home</a></li>
  <li><a class='prett' href='#' title='Menu'>Menu</a>
    <ul class='menus'>
      <li class='has-submenu'><a class='prett' title='Dropdown 1'>Dropdown 1 + Sub Menu</a>
        <ul class='submenu'>
          <li><a href="#" title="Sub Menu">Sub Menu</a></li>
          <li><a href="#" title="Sub Menu">Sub Menu 2</a></li>
          <li><a href="#" title="Sub Menu">Sub Menu 3</a></li>
        </ul>
      </li>
      <li><a href='#' title='Dropdown 2'>Dropdown 2</a></li>
      <li><a href='#' title='Dropdown 3'>Dropdown 3</a></li>
    </ul>
  </li>
  <li><a class='prett' href='#' title='Menu'>Menu</a>
    <ul class='menus'>
      <li class='has-submenu'><a class='prett' title='Dropdown 1'>Dropdown 1 + Sub Menu</a>
        <ul class='submenu'>
          <li><a href="#" title="Sub Menu">Sub Menu</a></li>
          <li><a href="#" title="Sub Menu">Sub Menu 2</a></li>
          <li><a href="#" title="Sub Menu">Sub Menu 3</a></li>
        </ul>
      </li>
      <li><a href='#' title='Dropdown 2'>Dropdown 2</a></li>
      <li><a href='#' title='Dropdown 3'>Dropdown 3</a></li>
    </ul>
  </li>
  <li><a class='prett' href='#' title='Menu'>Menu</a>
    <ul class='menus'>
      <li class='has-submenu'><a class='prett' title='Dropdown 1'>Dropdown 1 + Sub Menu</a>
        <ul class='submenu'>
          <li><a href="#" title="Sub Menu">Sub Menu</a></li>
          <li><a href="#" title="Sub Menu">Sub Menu 2</a></li>
          <li><a href="#" title="Sub Menu">Sub Menu 3</a></li>
        </ul>
      </li>
      <li><a href='#' title='Dropdown 2'>Dropdown 2</a></li>
      <li><a href='#' title='Dropdown 3'>Dropdown 3</a></li>
    </ul>
  </li>
  <li><a class='prett' href='#' title='Menu'>Menu</a>
    <ul class='menus'>
      <li class='has-submenu'><a class='prett' title='Dropdown 1'>Dropdown 1 + Sub Menu</a>
        <ul class='submenu'>
          <li><a href="#" title="Sub Menu">Sub Menu</a></li>
          <li><a href="#" title="Sub Menu">Sub Menu 2</a></li>
          <li><a href="#" title="Sub Menu">Sub Menu 3</a></li>
        </ul>
      </li>
      <li><a href='#' title='Dropdown 2'>Dropdown 2</a></li>
      <li><a href='#' title='Dropdown 3'>Dropdown 3</a></li>
    </ul>
  </li>
  <li><a class='prett' href='#' title='Menu'>Menu</a>
    <ul class='menus'>
      <li class='has-submenu'><a class='prett' title='Dropdown 1'>Dropdown 1 + Sub Menu</a>
        <ul class='submenu'>
          <li><a href="#" title="Sub Menu">Sub Menu</a></li>
          <li><a href="#" title="Sub Menu">Sub Menu 2</a></li>
          <li><a href="#" title="Sub Menu">Sub Menu 3</a></li>
        </ul>
      </li>
      <li><a href='#' title='Dropdown 2'>Dropdown 2</a></li>
      <li><a href='#' title='Dropdown 3'>Dropdown 3</a></li>
    </ul>
  </li>
  </ul>
  </nav>

例子

https://jsfiddle.net/mwb2caht/

image of submenu before fix and after

【参考方案1】：

使用这里的信息，它是关于 @media 查询的。 你可以给特定的屏幕尺寸指定属性

https://www.w3schools.com/css/css3_mediaqueries_ex.asp

编辑：您可以在浏览器窗口（在 Chrome 上）中按 F12，然后按 ctrl + shift + M 以获得响应式“测试器”

【讨论】：

实际上这不会正确工作，因为框的宽度可能不同，我正在寻找的是用 js 来确定第 2 层和第 3 层是否超出边界并将它们移动到左侧如果需要。我用屏幕截图编辑我的问题

你有解决办法了吗？

你是怎么解决的？

这是另一个同样问题的问题，有解决方案***.com/questions/11512032/…

感谢链接，它真的帮助了我