title: Attribute :value binding in select tag doesn't update inside Vue 3 component template (Composition API)
body: <p>I have a drop down menu where options are enumerated and shuffled, so that the selected option becomes the first. This script is working as intended:</p>
  <pre class="lang-html prettyprint-override"><code>&lt;div id=&quot;main&quot;&gt;
    &lt;sub-select :subs=&quot;data&quot; @comp-update=&quot;onShufflePaths($event)&quot;&gt;&lt;/sub-select&gt;
  &lt;/div&gt;
  </code></pre>
  <p>. .</p>
  <pre class="lang-js prettyprint-override"><code> const ui = {
     setup() {
      
      let data = ref('first_second_thrid');
      
      const onShufflePaths = (ind) =&gt; {
          let subs = data.value.match(/[^_]+/g);
          const main = subs.splice(ind, 1)[0];
          data.value = [main, ...subs].join('_');
      }
          
       return {
         data, onShufflePaths, 
       };
     },
   };
  
   const vueApp = createApp(ui);
   
  vueApp.component('sub-select', {
    props: ['subs'],
    emits: ['comp-update'],
    setup(props, { emit }) {
    
          let subs = computed(() =&gt; props.subs.match(/[^_]+/g));
      
      let subpath = computed(() =&gt; '0: ' + subs.value[0]);
      
      function onChange(evt) {
          emit('comp-update', evt.slice(0,1));                      
      } 
      
      return { subs, subpath, onChange };
    },
    template: `
    &lt;select :value=&quot;subpath&quot; @change=&quot;onChange($event.target.value)&quot;&gt;
      &lt;option v-for=&quot;(v,k) in subs&quot;&gt;{{k}}: {{v}}&lt;/option&gt;
    &lt;/select&gt; {{subpath}}`
  });
   
   vueApp.mount('#main');
  
  </code></pre>
  <p>The problem is, if I delete {{subpath}} from the template, the drop down menu comes up with no options selected by default. It looks like :value=&quot;subpath&quot; by itself is not enough to update subpath variable when props update, if it's not explicitly mentioned in the template.</p>
  <p>How can I make it work?</p>
  <p>Basically, I need the first option always to be selected by default.</p>
  <p>Thank you!</p>
  <p><a href="https://jsfiddle.net/tfoller/uy7k1hvr/26/" rel="nofollow noreferrer">https://jsfiddle.net/tfoller/uy7k1hvr/26/</a></p>