Two Ways to Write Vue Components
Vue.js 3 offers two component authoring styles: the familiar Options API and the newer Composition API. Both produce the same output—they are different ways to organize the same reactive system. The question is which style fits your project and team.
Options API: Structure by Type
The Options API groups code by type: data(), computed, methods, watch, and lifecycle hooks. For small components, this is clean and readable. New developers instantly know where to find state vs logic. The downside appears in large components where a single feature's code is scattered across multiple options—the search query lives in data(), the debounced watcher in watch, the fetch function in methods, and the cleanup in unmounted().
For teams migrating from Vue 2, the Options API provides continuity. Your existing components work with minimal changes. The learning curve is nearly zero. For projects where components stay small and focused, the Options API remains a perfectly valid choice.
Composition API: Structure by Feature
The Composition API lets you group related state, computed properties, and functions together inside the setup() function or <script setup> block. A search feature's reactive query, debounced watcher, and fetch function live in one block. Extract it into a useSearch() composable and reuse it across components—something the Options API cannot do without mixins.
The <script setup> syntax in Vue 3 makes the Composition API even more concise. Variables and functions declared at the top level are automatically available in the template—no explicit return statement needed. Components imported in <script setup> are automatically registered. The result is less boilerplate and more direct code.
TypeScript Support
The Composition API was designed with TypeScript in mind. ref<string>('') and computed<number>(() => ...) provide full type inference. The Options API requires a defineComponent() wrapper and complex type gymnastics for the this context. If your team uses TypeScript, the Composition API is the clear winner—type errors appear at write time, not at runtime.
Code Reusability: Composables vs Mixins
Composables replace mixins, which suffered from implicit dependencies and naming collisions. A composable is a plain function that returns reactive state—transparent, testable, and composable with other composables. You can see exactly what data and methods a composable provides by looking at its return value. With mixins, you had to read the mixin source to understand what it injected into your component.
Build a library of composables for common patterns: useLocalStorage(), useDebounce(), usePagination(), useAuth(). Each is a standalone function with explicit inputs and outputs, testable in isolation with standard unit testing tools. This composable pattern has become the standard way to share logic in the Vue ecosystem.
Performance Considerations
Both APIs compile to the same underlying reactive system, so runtime performance is identical. However, the Composition API enables better tree-shaking. Since composables are imported explicitly, bundlers can eliminate unused code more effectively. In large applications with many shared utilities, this can meaningfully reduce bundle size.
When to Use Which
Use the Options API for small projects, prototypes, and teams new to Vue. Use the Composition API for TypeScript projects, large-scale applications, and shared logic libraries. Many teams adopt a hybrid: Options API for simple pages, Composition API for complex features and shared composables. Vue 3 supports both styles in the same project without any configuration.
Conclusion
The Composition API is the future of Vue development, and the ecosystem is moving in that direction. New libraries, documentation, and tooling increasingly assume Composition API usage. If you are starting a new project, default to the Composition API with <script setup>. If you are maintaining an existing Options API codebase, migrate incrementally—convert complex components first where the benefits are most visible.
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