Unlocking Vue’s Composition API: A Modern Approach to Component Logic

This blog post explores the core concepts, benefits, and best practices of the Composition API—helping you decide when and how to adopt it in your Vue projects.

Why the Composition API?

1. Better Code Organization

In large components, the Options API can scatter related logic across different sections. The Composition API allows you to group related logic together, making components easier to understand and maintain.

2. Improved Reusability

With the Composition API, you can extract logic into reusable functions (called composables), reducing duplication and promoting cleaner architecture.

3. Enhanced TypeScript Support

The function-based nature of the Composition API works seamlessly with TypeScript, providing better type inference and autocompletion compared to the Options API.

4. More Flexibility

Since logic is composed using functions, you have fine-grained control over reactivity, side effects, and lifecycle hooks.

Core Concepts of the Composition API

1. ref() and reactive()

• ref() creates a reactive reference to a single value (works with primitives like numbers and strings).
• reactive() makes an entire object reactive, ideal for complex state structures.

2. computed()

Just like computed properties in the Options API, computed() lets you define derived state that updates automatically when dependencies change.

3. Lifecycle Hooks

Instead of using created(), mounted(), etc., the Composition API provides hooks like:

• onMounted()
• onUpdated()
• onUnmounted()

These are imported and called inside setup().

4. watch() and watchEffect()

• watch() tracks specific reactive dependencies and runs a callback when they change.
• watchEffect() automatically tracks dependencies and re-runs whenever any reactive value inside it updates.

When Should You Use the Composition API?

Complex Components – When a component has multiple interconnected pieces of logic.
Reusable Logic – When you want to share stateful logic across components.
TypeScript Projects – For better type safety and IDE support.
Large-Scale Apps – For improved maintainability and scalability.

You don’t need to rewrite existing components—the Options API still works perfectly fine. Instead, consider adopting the Composition API gradually, starting with new features or complex refactors.

The <script setup> Syntax: A Simpler Approach

Vue 3.2 introduced <script setup>, a compile-time syntactic sugar that reduces boilerplate. It automatically exposes top-level bindings to the template, making the Composition API even more concise.

This syntax is optional but highly recommended for its cleaner and more intuitive structure.

Final Thoughts

The Composition API represents a modern, scalable way to build Vue applications. While it requires a slight mindset shift from the Options API, the benefits in code organization, reusability, and TypeScript support make it a powerful tool for Vue developers.

If you’re starting a new Vue 3 project or refactoring a complex component, give the Composition API a try—you might never look back!

What’s your experience with the Composition API? Let me know in the comments.