css - 如何修复CSS中的动画故障？

Question

我正在尝试创建一个简单的侧边菜单，其中包含与其宽度变化相匹配的动画。当菜单关闭时，我只想显示图标，当它打开时，我想同时显示 - 图标和文本。动画效果很好，但切换时会出现某种故障……当文本出现时，它似乎与图标断线了。菜单打开时，如何相应地延迟文本显示？

Fiddle

HTML

     <div ng-app class="container" ng-controller="MyCtrl">
        <div class="row">
        <div class="col-md-3"><button class="btn btn-success" ng-click="toggleSideMenu()">
              <i class="fa fa-bars"></i></button>
          <div class="side-menu-wrapper" ng-class="{'menu-open':!!isMenuExpanded, 'menu-closed':!isMenuExpanded}">
            <ul class="list-group">
              <li class="list-item">
                <i class="fa fa-cog">
                  </i><span>
                    First item</span></li>
              <li class="list-item">
                <i class="fa fa-book"></i>
                <span>
                    First item</span></li>
              <li class="list-item">
                <i class="fa fa-pencil"></i>
                <span>
                    First item</span></li>
            </ul>
          </div>
        </div>
        <div class="col-md-9">

        </div>
      </div>
    </div>

CSS

    .container {
      margin-top: 15px;
    }

    .side-menu-wrapper {
      background-color: rgb(41, 44, 90);
      height: 100vh;
      transition: width 0.5s ease-in;
    }

    .side-menu-wrapper span {
      margin-left: 5px;
    }

    .side-menu-wrapper.menu-closed {
      width: 15%;
    }

    .side-menu-wrapper.menu-closed span {
      /* display: none;
      opacity: 0; */
      transition: opacity 1s ease-out;
      opacity: 0;
      height: 0;
      overflow: hidden;
    }

    .side-menu-wrapper.menu-open span {
      display: inline-block;
      float: right;
      opacity: 1;
    }

    .side-menu-wrapper.menu-open {
      opacity: 1;
      transition: width 0.5s ease-out;
      width: 100%;
    }

    .list-item {
      background-color: transparent;
      color: rgb(161, 165, 224);
      position: relative;
      display: flex;
      padding: 10px 15px;
      border-bottom: 1px solid rgb(161, 165, 224);
    }

Angular

  function MyCtrl($scope) {
    $scope.isMenuExpanded = false;
    $scope.toggleSideMenu = function() {
      $scope.isMenuExpanded = !$scope.isMenuExpanded;
    }
  }

Answer 1

问题是在.side-menu-wrapper.menu-closed span中设置height: 0;引起的

改变

    .side-menu-wrapper.menu-closed span {
      /* display: none;
      opacity: 0; */
      transition: opacity 1s ease-out;
      opacity: 0;
      height: 0;
      overflow: hidden;
    }

到

   .side-menu-wrapper.menu-closed span {
      /* display: none;
      opacity: 0; */
      transition: opacity 1s ease-out;
      opacity: 0;
      overflow: hidden;
    }

和

   .side-menu-wrapper span {
      margin-left: 5px;
    }

到

   .side-menu-wrapper span {
      margin-left: 5px;
      opacity: 0;
      white-space: nowrap;
    }