Lifecycle hooks in Composition API in Vue - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of lifecycle hooks in Vue's Composition API?

Lifecycle hooks let you run code at specific times during a component's life, like when it starts, updates, or stops. They help manage side effects and resource cleanup.

beginner

Name three common lifecycle hooks used in Vue's Composition API.

Three common hooks are onMounted (runs after the component is added to the page), onUpdated (runs after reactive data changes update the DOM), and onUnmounted (runs after the component is removed from the DOM).

beginner

How do you use onMounted in the Composition API?

Import <code>onMounted</code> from Vue, then call it inside the <code>setup()</code> function with a callback. This callback runs after the component appears on the page.

intermediate

What is the difference between onBeforeUnmount and onUnmounted?

onBeforeUnmount runs just before the component is removed, letting you clean up resources early. onUnmounted runs right after the component is removed from the DOM.

intermediate

Why is it better to use lifecycle hooks inside setup() in Composition API instead of Options API?

Using hooks inside setup() groups related logic together, making code easier to read and maintain. It avoids scattering lifecycle code across different options like mounted or updated.

Which lifecycle hook runs after the component is added to the DOM in Vue's Composition API?

A onMounted

B onUpdated

C onUnmounted

D onBeforeMount

onMounted runs after the component is inserted into the DOM, perfect for starting side effects.

Where do you place lifecycle hooks when using Vue's Composition API?

A Outside the component definition

B Inside the <code>setup()</code> function

C Inside the <code>methods</code> option

D Inside the <code>data()</code> option

Lifecycle hooks are called inside setup() to keep logic organized.

Which hook would you use to clean up timers or event listeners before a component is removed?

A onMounted

B onUpdated

C onBeforeUnmount

D onCreated

onBeforeUnmount is used to clean up resources before the component disappears.

What does the onUpdated hook do in Vue's Composition API?

A Runs only once when the app starts

B Runs before the component is mounted

C Runs when the component is destroyed

D Runs after reactive data changes update the DOM

onUpdated runs after the DOM updates due to reactive data changes.

Which import is needed to use lifecycle hooks in Vue's Composition API?

A import { onMounted } from 'vue'

B import { useEffect } from 'vue'

C import { lifecycle } from 'vue'

D import { componentDidMount } from 'vue'

Vue provides lifecycle hooks like onMounted directly from the 'vue' package.

Explain how to use lifecycle hooks in Vue's Composition API and why they are useful.

Think about when you want to run code during a component's life.

Describe the difference between onBeforeUnmount and onUnmounted hooks in Vue's Composition API.

Consider when you want to stop timers or listeners.