JavaScript小案例-树形菜单(菜单数据为数组)

news2024/11/17 1:31:15

菜单层级理论上可以无限多，因为是递归渲染。

gif演示图：
在这里插入图片描述
代码：
树形菜单.html

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>树形菜单-数组</title>
  <style>
    * {
      padding: 0;
      margin: 0;
      box-sizing: border-box;
      font-size: 14px;
      color: #fff;
    }

    body {
      background-color: #222;
    }

    .aside-menu {
      position: fixed;
      padding: 20px;
      width: 300px;
      height: 700px;
      background-color: #333;
      overflow: auto;
    }

    ul {
      list-style: none;
    }

    .aside-menu a {
      display: block;
      text-decoration: none;
      height: 30px;
      line-height: 30px;
    }

    .active {
      color: #00ff30;
    }

    .aside-menu a:hover {
      background-color: #727171;
    }

    [data-childs]::after {
      content: '-';
      float: right;
    }

    .expand::after {
      content: '+';
      float: right;
    }

    .notdisplay {
      display: none;
    }
  </style>
</head>

<body>
  <div class="aside-menu">
    <ul class="menuwrapper">

    </ul>
  </div>
  <script>
    // 菜单数据集合
    let menuArray = [
      {
        id: '0',//菜单id
        name: '树形菜单',//菜单名
        submenu: [//子菜单集合
          {
            id: '0',
            name: '菜单',
            submenu: [
              {
                id: '0',
                name: '菜单',
                submenu: [{
                  id: '0',
                  name: '菜单',
                  submenu: []
                },
                {
                  id: '0',
                  name: '菜单',
                  submenu: [{
                    id: '0',
                    name: '菜单',
                    submenu: []
                  }, {
                    id: '0',
                    name: '菜单',
                    submenu: []
                  }, {
                    id: '0',
                    name: '菜单',
                    submenu: []
                  }, {
                    id: '0',
                    name: '菜单',
                    submenu: []
                  },]
                },
                ]
              },
            ]
          },
        ]
      },
      {
        id: '0',
        name: '菜单',
        submenu: [
          {
            id: '0',
            name: '菜单',
            submenu: []
          },
        ]
      },
      {
        id: '0',
        name: '菜单',
        submenu: []
      }, {
        id: '0',
        name: '菜单',
        submenu: []
      }, {
        id: '0',
        name: '菜单',
        submenu: []
      }, {
        id: '0',
        name: '菜单',
        submenu: []
      }, {
        id: '0',
        name: '菜单',
        submenu: []
      }, {
        id: '0',
        name: '菜单',
        submenu: []
      }, {
        id: '0',
        name: '菜单',
        submenu: []
      }, {
        id: '0',
        name: '菜单',
        submenu: [
          {
            id: '0',
            name: '菜单',
            submenu: []
          }, {
            id: '0',
            name: '菜单',
            submenu: []
          }, {
            id: '0',
            name: '菜单',
            submenu: [{
              id: '0',
              name: '菜单',
              submenu: []
            }, {
              id: '0',
              name: '菜单',
              submenu: []
            },]
          },
        ]
      }, {
        id: '0',
        name: '菜单',
        submenu: []
      }, {
        id: '0',
        name: '菜单',
        submenu: []
      },
    ]

    /**
     * menuData-菜单数组
     * menuwrapper-当前菜单项包裹盒子
     * level-菜单层级，L0,L1,L2,...
     * paddingLeft-当前菜单的子菜单左内边距，制造树形缩进效果
     * paddingLeftIncrement-每层菜单左内边距增加值，默认20（px）
     */
    function renderMenu(menuData, menuwrapper, level = 0, paddingLeft = 0, paddingLeftIncrement = 20) {
      if (menuData && menuData.length > 0) {
        let l = level
        menuwrapper.classList.add(`L${l}`)
        menuwrapper.style.paddingLeft = `${paddingLeft}px`
        for (let i = 0; i < menuData.length; i++) {
          /** 
           * <ul class="menuwrapper">
           *  <li class="menuitem">
           *   <a href="#" data-childs="3" class="expand"><span class="active">菜单名</span>::after</a>
           *   <ul class="notdisplay">
           *    </ul>
           *  </li>
           * </ul>
           */
          const menuItem = document.createElement('li')
          menuItem.classList.add('menuitem')
          const link = document.createElement('a')
          link.href = '#'
          link.innerHTML = `<span>${menuData[i].name}</span>`
          menuItem.appendChild(link)
          menuwrapper.appendChild(menuItem)
          const submenu = menuData[i].submenu
          if (submenu.length > 0) {
            l++
            link.dataset.childs = submenu.length
            const submenuWrapper = document.createElement('ul')
            // 展开折叠图标切换、子菜单显示隐藏切换
            link.addEventListener('click', () => {
              link.classList.toggle('expand')
              link.nextElementSibling.classList.toggle('notdisplay')
            })
            paddingLeft = paddingLeftIncrement
            // 递归渲染子菜单数组
            renderMenu(submenu, submenuWrapper, l, paddingLeft)
            menuItem.appendChild(submenuWrapper)
          }
        }
      }
    }

    const menuwrapper = document.querySelector('.menuwrapper')
    // 活跃菜单
    menuwrapper.addEventListener('click', (e) => {
      if (e.target.tagName === 'A') {
        let activeLink = document.querySelector('.active')
        if (activeLink) activeLink.classList.remove('active')
        e.target.firstElementChild.classList.add('active')
      }
    })

    // 渲染
    renderMenu(menuArray, menuwrapper)
    // 释放菜单数据
    menuArray = null
  </script>
</body>

</html>