Vue.js is a progressive JavaScript framework for building user interfaces. Key features include reactive data binding, component-based architecture, virtual DOM, directives, computed properties, and lifecycle hooks. Supports both Options API and Composition API.
Vue 3 introduces Composition API, improved TypeScript support, multiple root elements, Teleport, Fragments, and better performance. Also includes improved reactivity system based on Proxy, and smaller bundle size.
Register components globally using app.component() or locally in components option. Support async components. Handle component naming conventions. Implement dynamic registration.
Configure Vue application using createApp() method. Set global options, plugins, and components. Configure via vue.config.js for CLI projects. Handle environment variables and build settings.
Use component element with :is binding. Handle component switching. Support keep-alive. Implement lazy loading. Handle transition effects.
Implement async data fetching in created/mounted hooks or setup(). Handle loading states. Support error handling. Implement data caching.
Use render functions for programmatic template creation. Handle virtual DOM nodes. Support JSX. Implement render helpers. Handle render optimization.
Create Vue projects using Vue CLI with 'vue create project-name' or quick start using CDN. Vue CLI provides project scaffolding, development tools, and build setup. Also supports Vite with 'npm init vue@latest'.
Vue instance goes through creation (setup data observation), mounting (DOM compilation), updating (re-render), and destruction phases. Each phase has associated lifecycle hooks like created(), mounted(), updated(), and unmounted().
Define data using data() function returning object in Options API or ref()/reactive() in Composition API. Data properties are reactive and trigger view updates when changed.
Computed properties are cached, reactive data properties that update when dependencies change. Define using computed option or computed() function. More efficient than methods for derived values.
Handle events using v-on directive or @ shorthand. Support event modifiers, arguments, and method calls. Example: @click='handleClick' or v-on:submit.prevent='handleSubmit'.
Directives are special attributes with v- prefix that apply reactive behavior to DOM. Common directives include v-if, v-for, v-bind, v-model, v-on. Can create custom directives.
Use v-if, v-else-if, v-else for conditional rendering. v-show for toggle visibility. v-if removes/adds elements from DOM, v-show toggles display property.
Create plugins using install method. Handle plugin options. Support global features. Implement plugin API. Handle plugin initialization.
Create filters for value transformation in Vue 2. Replace with methods or computed properties in Vue 3. Handle filter chaining. Implement global filters.
Use provide/inject for dependency injection. Handle injection inheritance. Support reactive injection. Implement injection key management.
Implement complex state patterns. Handle state persistence. Support state synchronization. Implement state machines. Handle state optimization.
Create complex event systems. Handle cross-component communication. Support event buses. Implement communication patterns. Handle event optimization.
Use watch option or watch() function to react to data changes. Support deep watching, immediate execution. Handle async operations. Implement cleanup functions.
Create mixins to share component logic. Handle mixin merging. Support global mixins. Implement mixin lifecycle. Handle mixin conflicts.
