title: How to get selected row index on @change event of child Select Dropdown in Element UI?
body: <p>I'm generating a list of multiple input elements in which one is <code>&lt;el-select&gt;</code>. On changing this select menu, I'm getting value bounded with that select. But here, question is, I also want to get index/row number of the parent v-for items.
  You can understand what I meant from the following code:</p>
  
  <pre><code>&lt;el-form-item v-for="(domain, index) in Prescription.domains"&gt;
      &lt;div class="col-md-2" v-if="medicineIsSelected === true"&gt;
          &lt;small&gt;Select Brand:&lt;/small&gt;
          &lt;el-select v-model="domain.SelectedBrand" clearable placeholder="Select" @change="updateDropdowns"&gt; &lt;!-- Here I want to pass {{index}} also --&gt;
            &lt;el-option
              v-for="item in selectedMedicineMetaInfo.BrandName"
              :key="item.value.name"
              :label="item.value.name"
              :value="item.value.rxcui"&gt;
            &lt;/el-option&gt;
          &lt;/el-select&gt;
      &lt;/div&gt;
  &lt;/el-form-item&gt;
  </code></pre>
  
  <p>As you can see from above code, I want to pass index in <code>updateDropdowns</code>.
  I tried passing updateDropdowns(index), here I got the index number but lost the selected value of that dropdown. How can I pass both?</p>