The main difference between Vue 3's Composition API and Options API is the code organization method, logical reuse mode and development experience. 1. In terms of code organization, the Options API stores logic in scattered by options (such as data and methods), which is suitable for beginners but complex components are easily confused; the Composition API groups logic by functions to improve maintainability. 2. In terms of reusability, the Options API relies on mixins to easily cause naming conflicts, while the Composition API enhances modularity and testability through custom function encapsulation logic. 3. In terms of learning curve, the Options API structure is intuitively suitable for small projects, and the Composition API is more powerful and compatible with TypeScript. It is suitable for large applications, but the two are not replace relationships but complementary tools.

When Vue 3 came out, one of the biggest changes was introducing the Composition API along the existing Options API. So what's the real difference? It's not just about syntax — it's about how you organize and reuse logic in your components.

1. Code Organization: Split Concerns vs. Group by Logic

With the Options API , everything is split into predefined options like data , methods , computed , and lifecycle hooks . This makes sense for beginners because it gives a clear structure. But as components grow, related code can get scattered across different sections.

The Composition API lets you group code by logical concern instead. You can keep all the code related to a specific feature (like form handling or data fetching) together, even if it involves reactive state, methods, and lifecycle logic.

• Example:
  • In Options API: form data in data() , validation in methods , side effects in mounted
  • In Composition API: all form-related logic can be grouped inside a setup() function or a custom composition function

This often makes complex components easier to read and maintain.

2. Reusability: Mixins vs. Custom Functions

In the Options API , reusing logic between components usually means using mixins. But mixins can cause naming conflicts and make it hard to track where certain behavior is coming from.

The Composition API encourages creating reusable functions that encapsulate logic. These functions can return reactive state, methods, or even handle lifecycle logic without polluting component scope.

• For example:
  • A useFetch function can handle data loading, error states, and refetching
  • A useFormValidation function can manage validation rules and error messages

This leads to more modular and testable code, especially in large apps.

3. Learning Curve and Readability

If you're new to Vue or working on small projects, the Options API might feel more approachable. Its structure is predictable, and the learning curve is gentler.

But once you start dealing with larger components or want to share logic more cleanly, the Composition API becomes more powerful. It also plays well with TypeScript and offers better type inference.

Still, this doesn't mean the Options API is outdated — it's still fully supported and useful for many cases. The key is choosing based on your project needs and team familiarity.

So yeah, the main differences come down to organization style, reusability patterns, and developer experience. Neither is strictly better — they're just tools for different situations.

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