Page 10 - Vue.js

A form that only tells the user after submitting that the email address is already taken creates avoidable frustration. Professional form implementation in Vue 3 means detecting dirty state, showing validation at the right moment, and integrating asynchronous checks cleanly with debounce and a loading state.

A direct fetch call that throws JSON at the template is not an API layer, it is a maintenance problem waiting to happen. DTOs, structured error mapping, and retry logic turn a Vue REST API integration into a stable layer you can actually rely on.

Rewriting a large project from scratch for a Nuxt 2 to Nuxt 3 migration is rarely realistic. With Nuxt Bridge as an intermediate step and a clear order for Vuex, asyncData and module replacement, the migration can happen in manageable, testable stages instead of stalling the project for weeks.

A poorly designed Component API in a shared component library creates extra work for every team member who uses it. Props without default values, Emits without type contracts, missing slots for composition points and an undocumented Expose interface all make components hard to use. With clear conventions and TypeScript, Component APIs emerge that are stable, extensible and backwards-compatible.

A PWA with Vue and Vite turns an existing web application into an installable, offline capable app, without app store review and without a separate native codebase. With vite-plugin-pwa, service worker, web app manifest, and caching strategies can be configured largely automated, while update handling and offline behavior get tailored specifically to the application at hand.

Composables are the most important reuse mechanism in Vue 3, but how do you test reactive logic that registers lifecycle hooks, depends on timers, or makes fetch calls? Composable testing is not a special case of component testing, it is its own approach with its own tools and patterns.

Props flow down, emits flow up. One-way data flow in Vue.js is not a design dogma, it is the foundation for predictable, debuggable component behavior. Anyone who mutates props builds bugs that only surface under load or with complex state changes.

A collection of reusable Vue components is not yet a design system. Only design tokens as a single source of truth for colors and spacing, a deliberately designed component API and firm versioning turn loose building blocks into a system that teams can use consistently across project boundaries.

Reactivity Transform promised reactive values without .value, destructurable directly like normal variables. The compiler experiment was officially dropped in 2023. If you read old code or old blog posts about it today, you should understand how it worked, why it failed, and what remains relevant for practice.

The Composition API gives developers maximum freedom when structuring components, and that is exactly the problem. Without clear conventions, setup() functions grow into unreadable blocks of a hundred lines with mixed logic. This guide shows how to structure the Vue Composition API so components stay maintainable, even as they grow complex.