What is the reason behind Vue not updating the array order in $ref when unshift is used?

Here's an interesting example to ponder:

<template>
  <div>
    <button @click="addItem">Add Item</button>
    <h1>Fruits</h1>
    <ul>
      <li
        v-for="(item, index) in items"
        ref="items"
        v-bind:key="item.id"
        @click="logIndex(index)"
      >
        {{ item.name }}
      </li>
    </ul>
  </div>
</template>

<script>
export default {
  name: "Fruits",
  data() {
    return {
      items: [
        { name: "apple", id: 1 },
        { name: "banana", id: 2 },
      ],
    };
  },
  methods: {
    addItem() {
      const nextNumber = Math.max(...this.items.map((x) => x.id)) + 1;
      this.items.unshift({
        name: "peach " + nextNumber,
        id: nextNumber,
      });
      console.log(this.$refs);
      console.log(this.items);
    },
    logIndex(index) {
      console.log(index);
      console.log(this.items[index]);
      console.log(this.$refs.items[index]); //this seems reasonable to assume
      //using the index here would return
      //the correct reference, but maybe not
    },
  },
};
</script>

Upon inspecting the console logs, it becomes evident that the order of refs and items is not consistent. Clicking on a fruit item will log that specific item, revealing the discrepancy. What could be causing this inconsistency? Do refs have a distinct order for a specific reason?

Explore this example further on CodeSandbox View demonstration

Unpacking the Issue:

Encountering this dilemma raised a critical question. Picture a scenario where a component comprises an array of child components. If the need arises to interact with a sibling component, emitting from the initiating component and handling the event on the parent component is a common practice. However, leveraging the index for direct access fails when the initial array undergoes modification. An alternative approach utilizing .find and matching on component data proved to be effective.

While adopting Vuex or a similar methodology may offer a more robust solution in the mentioned situation, an investigation into the discrepancy between this.$refs and the underlying data's sort order remains intriguing. Your insights on why this disparity exists and any workaround suggestions would be greatly appreciated.

Answer №1

In this code snippet, we can see a workaround example based on a discussion thread linked by @Michal. The workaround involves storing the index or another key as a DOM attribute and then retrieving it later when needed with $ref. While not the most ideal solution, it is currently the best workaround available. It would be preferable to find a method that does not rely on accessing $refs.

The reason for this behavior seems to be that the order of elements is not guaranteed in Vue for performance reasons. The reference is simply pushed onto the array.

refs[key].push(ref)

Answer №2

It's important to note that refs are not reactive, and the order of refs may not match the order of your source array. You can read more about this here.

While there are some workarounds mentioned in the thread, I personally prefer using a different strategy to implement the functionality without relying on refs.

Answer №3

Your information is not tied to the data. The numbering system using [0] for the first element, [1] for the second element, and so on, is how the connection is made between the references and the rendered elements.

Keep in mind that $refs are only populated once the component has been rendered, and they are not reactive. They are primarily used for direct child manipulation as a last resort.

Refer to the documentation for more insights

I concur with your thoughts on Vuex

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