Vue 3相較于Vue 2在多個(gè)關(guān)鍵方面進(jìn)行了改進(jìn)。1. Composition API提供更靈活的邏輯組織方式，允許將相關(guān)邏輯集中管理，同時(shí)仍支持Vue 2的Options API；2. 性能更優(yōu)且包體積更小，核心庫縮小約30%，渲染速度更快并支持更好的搖樹優(yōu)化；3. 響應(yīng)式系統(tǒng)改用ES6 Proxy，解決了Vue 2中無法自動追蹤屬性增刪的問題，使響應(yīng)式機(jī)制更自然一致；4. 內(nèi)置更好支持TypeScript、支持多根節(jié)點(diǎn)片段及自定義渲染器API，提升了靈活性和未來適應(yīng)性?？傮w而言，Vue 3是對Vue 2的平滑升級，在性能、可維護(hù)性和開發(fā)體驗(yàn)上有顯著提升。

Vue 3 brings several meaningful changes compared to Vue 2, especially in performance, code structure, and developer experience. If you're upgrading or starting a new project, here are the key differences that actually matter in practice.

1. Composition API vs Options API

Vue 3 introduces the Composition API, which gives developers more flexibility in organizing logic. It's an alternative to the traditional Options API (used in Vue 2), not a replacement.

• With the Composition API, you can group related logic together, instead of splitting it across data, methods, and computed.
• This helps especially in larger components where logic can get scattered.
• Example: Instead of writing a method in methods and a variable in data, you can define both inside a setup() function using ref and reactive.

If you’re used to Vue 2’s style, the Options API is still supported in Vue 3 — so you don’t have to switch right away.

2. Better Performance and Smaller Bundle Size

Vue 3 is faster and lighter out of the box.

• The core library is smaller — around 30% smaller than Vue 2.
• Rendering speed improved thanks to a more efficient virtual DOM implementation.
• Components compile into more optimized code, especially with <script setup></script> syntax.
• Tree-shaking is better supported, meaning unused features aren’t included in your final build.

This makes Vue 3 a stronger choice for apps where performance and loading speed matter, like mobile sites or large-scale applications.

3. Reactivity System Rewrite (Proxy instead of Object.defineProperty)

Vue 2 used Object.defineProperty to track data changes, which had some limitations:

• Couldn’t detect property additions or deletions unless using this.$set.
• Adding new properties to reactive objects was tricky.

Vue 3 uses ES6 Proxies, which:

• Track changes more naturally.
• Allow you to add or remove object properties without special syntax.
• Make reactivity system more consistent and easier to debug.

This change is mostly under the hood, but it removes some of the gotchas Vue 2 users were familiar with.

4. Support for TypeScript, Fragments, and Custom Renderer API

Some other notable upgrades:

• TypeScript support is built-in and much smoother. Vue 3 was rewritten in TypeScript, making types more accurate and easier to use.
• Fragments are allowed — components can return multiple root nodes now, unlike Vue 2 which required a single root element.
• Custom renderers can be created more easily, allowing Vue to target environments beyond the browser (like SSR, Canvas, or even WebGL).

These features make Vue 3 more flexible and future-proof, especially for teams using TypeScript or building advanced tooling.

Final Thoughts

The jump from Vue 2 to Vue 3 isn’t drastic if you're already familiar with Vue. Most concepts still apply, and Vue 3 feels like a refined version rather than a total rewrite. But the improvements in performance, maintainability, and developer ergonomics are real and impactful.

You don't need to rewrite everything tomorrow — Vue 3 is backward compatible enough that you can mix and match features. But for new projects or major updates, Vue 3 is definitely the way to go.

基本上就這些。

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