vuejs dropdown is set code example
Example: how to select specific option in vue
<select>
<option v-for="(item , index) in categories" v-bind:key="index" :selected= "item.id == 30" >
{{item.title}}
</option>
</select>
<select>
<option v-for="(item , index) in categories" v-bind:key="index" :selected= "item.id == 30" >
{{item.title}}
</option>
</select>