vue3实现tabs导航栏，点击每个导航项有下划线动画效果

<template>
  <div class="navigation">
    <div
      v-for="(item, index) in items"
      :key="index"
      class="navigation-item"
      :class="{ active: index === activeIndex }"
      @click="activeIndex = index"
      ref="itemRefs"
    >
      {
    
    {
    
     item }}
    </div>
    <div
      class="navigation-underline"
      :class="{ active: activeIndex !== -1 }"
      :style="underlineStyle"
      ref="underlineRef"
    ></div>
  </div>
</template>

<script setup>
import {
    
     ref, watch, onMounted } from "vue";
const activeIndex = ref(0);
const items = ref(["Home", "About", "Services", "Services"]);
const underlineStyle = ref({
    
    
  transform: "translateX(0)",
});

const itemRefs = ref([]);
const underlineRef = ref(null);

const updateUnderline = () => {
    
    
  // 获取标题的宽度，减去下划线的宽度除以2，可以使下划线在标题下居中显示
  const item = itemRefs.value[activeIndex.value];
  const underline = underlineRef.value;
  let newLeft = Number((item.offsetWidth - underline.offsetWidth)) / 2;
  if (item && underline) {
    
    
    const {
    
     offsetLeft } = item;
    console.log(offsetLeft);
    underlineStyle.value = {
    
    
      transform: `translateX(${
      
      offsetLeft + newLeft}px)`,
    };
  }
};

watch(activeIndex, () => {
    
    
  updateUnderline();
});

onMounted(() => {
    
    
  updateUnderline();
});
</script>

<style>
.navigation {
    
    
  width: 400px;
  display: flex;
  align-items: center;
  justify-content: space-around;
  position: relative;
  padding: 0 20px;
  height: 50px;
  font-size: 16px;
  font-weight: bold;
}

.navigation-item {
    
    
  cursor: pointer;
}

.navigation-item.active {
    
    
  color: #f00;
}

.navigation-underline {
    
    
  /* 下划线的宽度 */
  width: 50px;
  height: 3px;
  border-radius: 2px;
  position: absolute;
  bottom: 0;
  left: 0;
  background-color: #f00;
  transition: all 0.3s ease-in-out;
}

.navigation-underline.active {
    
    
  transform: translateY(-3px);
}
</style>

效果图：