Vue2 and Vue3: Core Differences and Project Selection Guide

Vue.js officially launched version 3.0 in 2020. This update is not a simple functional iteration, but a systematic refactoring around performance, development experience and maintainability.

Vue officials clearly recommend that Vue3 should be given priority to new projects, because Vue 2 has officially terminated official maintenance on December 31, 2023 and only provides extended support.

Core architecture changes, comprehensive innovation from the bottom to the top

The most fundamental change in Vue3 lies in the refactoring of its responsive system. Vue2 uses Object.defineProperty to hijack data getters and setters.

This mechanism has inherent limitations: it cannot detect the addition or deletion of object properties, and changes to the array need to be achieved by overriding the array method, which brings additional complexity and performance overhead.

Vue3 instead rewrites the responsive system with an ES6-based Proxy API. Proxy can directly proxy the entire object rather than hijacking attributes one by one.

This means that it can automatically listen for all operations on objects and arrays, including the addition and deletion of attributes, without special handling. This change not only makes responsive systems more powerful and intuitive, but also significantly simplifies the internal implementation of Vue, laying the foundation for performance improvements.

At the compiler and virtual DOM levels, Vue3 is deeply optimized. It introduces compile-time optimization strategies such as static promotion, which can identify static nodes in the template and promote them outside the rendering function, avoiding the repeated creation of these nodes every time it is rerendered.

Vue3 rewrites the diff algorithm of the virtual DOM to allow it to skip static subtrees and compare only dynamic parts when updated, resulting in a 1.2 to 2-fold performance improvement and more efficient server-side rendering (SSR).

Development experience evolves, and combined APIs bring a new paradigm

Vue2 uses the Options API to organize component logic and classify options such as data, methods, and computed. This approach is clear and understandable in small components, but when the components become complex, code that handles the same function is scattered among different options, reducing readability and maintainability.

Vue3 introduces the revolutionary Composition API, which is based on functional programming ideas that allow developers to encapsulate all the logic related to a specific function (responsive states, calculated properties, methods) in a single function.

This pattern allows the organization of code to be no longer limited by options, but around the business logic itself, making the logic of complex components clearer and naturally supporting excellent logic reuse.

In terms of TypeScript support, Vue3 was rewritten from scratch using TypeScript and provides complete type definitions. The design of the combined API is very friendly to type inference, allowing developers to obtain accurate autocompletion and type checking, which greatly improves the development experience and code robustness of large projects.

Framework size and ecology, a smaller and more modular future

Thanks to its modular architectural design, the core of Vue3 has been broken down into more fine-grained modules. Combined with the Tree-shaking feature of modern building tools, unused Vue APIs can be automatically removed when packaging projects, resulting in a smaller package. Official data shows that the minimized basic runtime of Vue3 is only about 10 KB after compression, which is lighter than Vue2.

Vue3 also brings some useful new built-in components.& lt; The Teleport component allows you to "transfer" a portion of a template to any other location in the DOM, making it ideal for handling scenarios such as global modal boxes and notification prompts that need to break through component-level constraints.

<The Suspense component provides a declarative way to handle asynchronous dependencies that gracefully control the loading state of asynchronous components during loading.

Vue3's ecosystem is becoming increasingly mature. Vue Router 4, state management library Pinia (as a successor to Vuex), and mainstream UI libraries such as Element Plus, Vant 4, etc. all provide stable support for Vue3. Although a few older plug-ins may not have yet been migrated, the overall ecosystem has completed the transition to Vue3.

Intuitive comparison, see the differences between Vue2 and Vue3 in one table

Project Selection and Migration Guide

For brand new projects, you should not hesitate to choose Vue3. It allows you to enjoy better performance, a better development experience and a longer technology life cycle from the beginning. The only exception is if the project must support Internet Explorer 11, because Vue3 uses modern JavaScript features that are not supported by IE11, you can only choose Vue2 at this time.

For existing large-scale Vue2 projects, if you don't encounter obvious performance bottlenecks or strong demand for new Vue3 features, you don't have to rush to migrate completely immediately. You can adopt a progressive strategy: try to use the Composition API (supported by Vue 2.7) in new functional modules or refactored components to gradually gain experience.

If you decide to migrate, be sure to read the official migration guide carefully and use the migration tools provided by Vue CLI to assist. Focus on some incompatible changes, such as the call method of global APIs, the usage of v-models, changes in lifetime hook names, etc.

The team's technical reserves are another key consideration. If the team is already familiar with Vue2 but has not been exposed to the combined API, it is pragmatic to use Vue2 in maintenance projects in the short term. But in the long run, getting the team to learn and move to Vue3 is a necessary investment that can avoid future technical debt.

With the comprehensive upgrade of the Vue ecosystem, a significant trend is that the community's mainstream libraries and tools have been built around Vue3. One developer wrote on a technology blog: "Vue3's composite API is not just written differently, it changes the way you think and organize front-end logic."

When the launcher for a new project starts running, and when complex business logic is elegantly encapsulated and reused, Vue3 represents not only a version change, but also an advancement in front-end engineering thinking.