Vue.js：转换动画在单击时不起作用

Question

I have an arrow icon inside a menu item. When I click on this item, a small additional menu drops down. I need to find a solution how to rotate my icon at the same time as my dropdown menu appears. My approach doesn't work.

Here is what I have in the Vue component:

     <nav>
        <section class="nav-item" @click="showDropdown = !showDropdown">
          <div class="nav-icon">
            <img src="../../../assets/img/users.svg" />
          </div>
          <h4>Users</h4>
          <div class="arrow" :class="arrowLeft">
            <img src="../../../assets/img/arrow_down.svg" />
          </div>
          <div v-if="showDropdown">
            <span class="sub-nav-item">Import</span>
            <span class="sub-nav-item">Invitations</span>
          </div>
        </section>
      <section class="nav-item">
        <div class="nav-icon">
          <img src="../../../assets/img/polls.svg" />
        </div>
        <h4>Poll</h4>
      </section>
    </nav>

In my script tags:

<script>
export default {
data() {
  return {
    showDropdown: false,
  };
},
computed: {
  arrowLeft() {
    let arrow = 'turn-arrow';
    if (this.showDropdown === true) {
      return arrow;
    }
    return true;
   },
 },
};
</script>

My CSS:

.arrow {
display: inline;
height: 7px;
width: 13px;
margin-left: 13px;
} 
.turn-arrow {
-moz-transform: rotate(90deg);
-ms-transform: rotate(90deg);
-webkit-transform: rotate(90deg);
transform: rotate(90deg);
}

Answer 1

Sometimes, rotate won't work on inline elements.

Try

.arrow {
    display: inline-block; /* or block */
}

See https://stackoverflow.com/a/28664701/5599288