What is Vue's reactivity system?

Vue's reactivity system is a core feature that automatically tracks dependencies and updates the DOM when data changes. In Vue 2, it uses getters/setters via Object.defineProperty, while Vue 3 uses JavaScript Proxies for better performance and more capabilities. When you modify reactive data, Vue automatically updates any part of your application that depends on that data, eliminating the need for manual DOM manipulation.

What are Vue components?

Vue components are reusable, self-contained pieces of UI that encapsulate HTML, CSS, and JavaScript. Each component has its own template, script, and style sections. Components can communicate with each other through props (parent to child), events (child to parent), and provide/inject patterns. They can be registered globally or locally, and can be written as Single File Components (.vue files) or using render functions.

What are Vue directives?

Directives are special attributes with the v- prefix that apply special reactive behavior to the DOM. Common built-in directives include v-bind for binding attributes, v-on for event handling, v-if/v-show for conditional rendering, v-for for list rendering, and v-model for two-way data binding. You can also create custom directives to encapsulate DOM manipulation logic.

What are Vue lifecycle hooks?

Lifecycle hooks are special methods that allow you to execute code at specific stages of a component's lifecycle. Common hooks include created (instance created), mounted (component added to DOM), updated (component re-rendered), and unmounted (component removed from DOM). In Vue 3's Composition API, these are available as composables like onMounted, onUpdated, etc.

How does Vue Router work?

Vue Router is the official routing library for Vue.js. It enables building Single Page Applications with multiple views. It supports nested routes, route parameters, navigation guards, and programmatic navigation. You define routes in a router configuration, then use to display matched components and for navigation. It also supports route-based code splitting for better performance.

What is Vuex and when should I use it?

Vuex is Vue's state management library using a centralized store pattern. It's useful for medium to large applications where state needs to be shared across many components. Vuex uses a unidirectional data flow with state, getters, mutations, and actions. For new projects, Pinia is now the recommended state management solution as it provides a simpler API with TypeScript support and better devtools integration.

What is the Composition API?

The Composition API is a new way of organizing component logic introduced in Vue 3. It provides a set of functions (like ref, reactive, computed, watch) that allow you to compose logic more flexibly than the Options API. It improves TypeScript support, code reusability through composables, and makes it easier to organize complex component logic. The Composition API can be used alongside the Options API.

How do I handle forms in Vue?

Vue provides v-model for two-way data binding on form inputs, making form handling straightforward. For complex forms, you can use computed properties for validation, watchers for side effects, and methods for submission. Libraries like VeeValidate provide comprehensive form validation solutions. You can also create custom form components that work with v-model by accepting a modelValue prop and emitting update:modelValue events.

What are Vue plugins?

Vue plugins are reusable packages that add global-level functionality to Vue. They typically include global methods, directives, transitions, or component options. Plugins are installed using Vue.use() in Vue 2 or app.use() in Vue 3. Examples include Vue Router, Vuex, and third-party libraries like vue-i18n for internationalization or vue-toastification for notifications.

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Vue.js FAQs

Find answers to frequently asked questions about Vue.js, the progressive JavaScript framework. Learn about components, reactivity, directives, and Vue ecosystem.

Vue.js is a progressive JavaScript framework used for building user interfaces. It's designed from the ground up to be incrementally adoptable, meaning you can use it for a small part of your application or scale it up to power a full-featured Single Page Application (SPA). Vue focuses on the view layer only, making it easy to integrate with other libraries or existing projects.

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