Why onUpdated and onBeforeUpdate in Vue? - Purpose & Use Cases

The Big Idea

Discover how Vue tells you exactly when your page changes so you never miss a beat!

The Scenario

Imagine you have a webpage where you want to run some code every time a part of the page changes, like updating a list or refreshing a counter. You try to do this by manually checking for changes and running code after every small update.

The Problem

Manually tracking changes is tiring and easy to mess up. You might forget to check some updates or run your code too early or too late. This makes your page buggy and slow because you repeat work or miss important updates.

The Solution

Vue's onBeforeUpdate and onUpdated hooks let you run code automatically just before and just after the page updates. This means you don't have to watch changes yourself; Vue tells you exactly when to act.

Before vs After

✗ Before

if(dataChanged) { doSomething(); updateDOM(); doSomethingAfter(); }

✓ After

onBeforeUpdate(() => { doSomething(); }); onUpdated(() => { doSomethingAfter(); });

What It Enables

This makes your app smarter and faster by running code at the perfect moment during updates without extra work.

Real Life Example

Think of a live chat app where you want to scroll to the newest message automatically. Using onUpdated, you can scroll right after new messages appear without complicated checks.

Key Takeaways

onBeforeUpdate runs code just before the page changes.

onUpdated runs code right after the page changes.

They help you handle updates cleanly and reliably without manual tracking.