onUpdated and onBeforeUpdate in Vue - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the onBeforeUpdate lifecycle hook do in Vue?

onBeforeUpdate runs right before the component updates its DOM. It lets you react just before changes appear on screen.

beginner

When is the onUpdated hook called in a Vue component?

onUpdated runs after the component's DOM has updated. It lets you run code once the screen shows the latest changes.

intermediate

How do onBeforeUpdate and onUpdated hooks help in Vue?

<p>They let you run code before and after the DOM updates. This helps manage side effects or animations tied to changes.</p>

intermediate

Show a simple example of using onBeforeUpdate and onUpdated in Vue's <script setup>.

<pre>import { ref, onBeforeUpdate, onUpdated } from 'vue'

const count = ref(0)

onBeforeUpdate(() =&gt; {
  console.log('About to update DOM')
})

onUpdated(() =&gt; {
  console.log('DOM updated')
})</pre>

beginner

Can onBeforeUpdate or onUpdated stop the update from happening?

<p>No. These hooks only let you react to updates. They cannot prevent or cancel the DOM update.</p>

When does onBeforeUpdate run in Vue?

A When the component is created

B Right after the DOM updates

C Right before the DOM updates

D When the component is destroyed

onBeforeUpdate runs just before the DOM changes are applied.

Which hook runs after the DOM has updated?

A onUpdated

B onMounted

C onBeforeUpdate

D onCreated

onUpdated runs after the DOM update is complete.

Can onBeforeUpdate stop the DOM update from happening?

A Yes, it can cancel the update

B No, it only runs before update

C Yes, if you return false

D Only if used with <code>onUpdated</code>

It cannot stop the update; it only lets you react before it happens.

Where do you import onBeforeUpdate and onUpdated from in Vue 3?

A vue-router

B vue-lifecycle

C vuex

D vue

Both hooks come from the main vue package.

Which Vue lifecycle hook would you use to run code after the DOM changes?

A onUpdated

B onUnmounted

C onBeforeUpdate

D onCreated

onUpdated runs after the DOM updates.

Explain the difference between onBeforeUpdate and onUpdated hooks in Vue.

Think about timing: before vs after the screen changes.

Describe a practical use case for onBeforeUpdate and onUpdated in a Vue component.

Consider what you might want to do right before or after the screen changes.