<template>
    <div class="transition">
        <button @click="isActive= !isActive">トランジション</button>
        <transition>
            <div v-if="isActive">こんにちは！</div>
        </transition>
    </div>
</template>

<script>
export default {
    data(){
        return{
            isActive: false
        }
    }
}
</script>

<style scoped>
.v-enter-active{
    transition: opacity 1s;
}
.v-leave-active{
    transition: opacity 1s;
}
.v-enter{
    opacity: 0;
}
.v-leave-to{
    opacity: 0;
}
</style>