v-for vue template

app.vue

<template>
     <div>
        <div 
        v-for="(item, i ) in items" 
        :key="i"
        :class="{ active: i === activeItem}"
        >
         // some looped items from data here
         // button for active toggle 
            <button @click="selectItem(i)"> make item active </button>
        </div>
    </div>
</template>