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Differences between VueJS 2 and VueJS 3

Differences between VueJS 2 and VueJS 3

Tinker

Vue.js 3 introduced several significant improvements and changes compared to Vue.js 2. Here are some key differences:

Composition API:

  • Vue.js 2: Relies on Options API where data, methods, computed properties, etc., are defined in a component's options object.
  • Vue.js 3: Introduces the Composition API, allowing logic to be organized using functions and making it easier to share and reuse code across components.
Install composition api and use in Vue2
In Vue3, no need to install composition

Reactivity System:

  • Vue.js 2: Uses Object.defineProperty for reactivity, which has some limitations and can be less performant for deep reactivity.
  • Vue.js 3: Uses a Proxy-based reactivity system, which provides better performance and supports deep reactivity without some of the limitations of Object.defineProperty.

Teleport:

  • Vue.js 2: Does not have a built-in teleport feature for moving an element to a different part of the DOM.
  • Vue.js 3: Introduces the teleport feature, allowing components to be rendered at a different place in the DOM.

Fragments:

  • Vue.js 2: Requires a single root element in each component template.
  • Vue.js 3: Supports multiple root elements in a component template, eliminating the need for unnecessary wrapper elements.

Global Mounting:

  • Vue.js 2: The global Vue instance is used to mount the root component.
  • Vue.js 3: Introduces createApp for creating the application instance and makes the mounting process more explicit.

Performance Improvements:

  • Vue.js 3: Includes various optimizations for better performance, including a faster virtual DOM, optimized component updates, and improved static tree hoisting.

TypeScript Support:

  • Vue.js 2: Has limited built-in TypeScript support.
  • Vue.js 3: Offers improved TypeScript support, with better type inference and more accurate type checking.

Custom Directives:

  • Vue.js 2: Custom directives are registered globally using Vue.directive.
  • Vue.js 3: Custom directives are registered using the app.directive method, making it more modular and scoped to the app instance.

Scoped Slots:

  • Vue.js 2: Scoped slots have some limitations, and passing multiple values can be challenging.
  • Vue.js 3: Introduces v-slots for improved handling of scoped slots, making it more flexible and powerful.

Tree-Shakable:

  • Vue.js 3: Is designed to be more tree-shakable, allowing bundlers to eliminate unused code during the build process for better optimization.

Better TypeScript Integration:

  • Vue.js 3: Provides improved TypeScript support, making it easier to work with TypeScript in Vue projects.

API Changes:

  • Vue.js 3: Introduces changes to some APIs, such as the nextTick function being replaced by a Promise-based nextTick method.

It's worth noting that while Vue.js 3 introduced many improvements, Vue.js 2 is still widely used, and migration to Vue.js 3 may depend on the specific needs and constraints of a project.