Vue 3 Composition API Patterns

Vue 3 with Composition API, Pinia stores, VueUse composables, and Vite for modern reactive apps.

Full-StackModerate

Stack Components

FrameworkVue 3.5

StatePinia 2

ComposablesVueUse

RouterVue Router 4

BuildVite 6

TestingVitest + Vue Test Utils

Why

Composition API enables logic reuse without mixins' naming collisions. Pinia is 1KB, type-safe, and DevTools-integrated.

VueUse provides 200+ tested composables (useFetch, useStorage, useIntersectionObserver). Vue 3.5's reactive props destructure is zero-cost.

When

Choose Vue 3 for progressive enhancement, teams familiar with it, and apps needing fine-grained reactivity. Avoid if team is React-only or for SSR-heavy apps (Nuxt adds complexity vs Next.js).

How

1. Scaffold — npm create vue@latest, select TypeScript + Pinia + Router 2. Setup syntax — <script setup lang="ts">, no boilerplate return statement 3. Composables — extract logic to useX.ts, return refs + functions 4. Pinia store — defineStore with state, getters, actions; use in components 5. VueUse — npm i @vueuse/core, use useFetch, useDark, useLocalStorage 6. Reactivity — ref() for primitives, reactive() for objects, computed() for derived 7. Testing — Vitest + @vue/test-utils, mount component, assert emitted events 8. Deploy — npm run build, deploy dist/ to any static host or Nuxt for SSR

Example

// stores/user.ts — Pinia store with TypeScript import { defineStore } from "pinia"; import { ref, computed } from "vue"; export const useUserStore = defineStore("user", () => { const users = ref<User[]>([]); const count = computed(() => users.value.length); const activeUsers = computed(() => users.value.filter((u) => u.active)); async function fetchUsers() { users.value = await fetch("/api/users").then((r) => r.json()); } return { users, count, activeUsers, fetchUsers }; }); // composables/useDebounce.ts — reusable logic import { ref, watch } from "vue"; export function useDebounce<T>(source: Ref<T>, delay = 300): Ref<T> { const debounced = ref(source.value) as Ref<T>; let timer: ReturnType<typeof setTimeout>; watch(source, (val) => { clearTimeout(timer); timer = setTimeout(() => (debounced.value = val), delay); }); return debounced; } // UserList.vue — setup syntax + Pinia + VueUse <script setup lang="ts"> import { useUserStore } from "@/stores/user"; import { useDebounce } from "@/composables/useDebounce"; import { useIntersectionObserver } from "@vueuse/core"; const store = useUserStore(); const search = ref(""); const debouncedSearch = useDebounce(search, 300); const target = ref<HTMLElement | null>(null); const { isActive } = useIntersectionObserver(target, ([{ isIntersecting }]) => { if (isIntersecting) store.fetchUsers(); }); </script> <template> <input v-model="search" placeholder="Search..." /> <div ref="target" v-if="isActive">Loading...</div> <ul v-else> <li v-for="u in store.activeUsers" :key="u.id">{{ u.name }}</li> </ul> </template>

Common Problems

⚠Destructuring reactive object loses reactivity — use toRefs() or storeToRefs() for Pinia
⚠watch vs watchEffect confusion — watch needs explicit sources, watchEffect auto-tracks
⚠v-for without :key — DOM updates break, always use unique item ID
⚠Mutating props — Vue warns, use v-model or emit events for parent-owned state

Best Practices

✓Use <script setup> — 30% less boilerplate, better tree-shaking, TS inference
✓Composables over mixins — named imports, no property collisions, tree-shakeable
✓Pinia setup stores — function syntax, full TS, use computed for getters
✓VueUse before custom code — 200+ tested composables, don't reinvent

FAQ

What is Vue 3 Composition API Patterns and what projects is it for?

Vue 3 with Composition API, Pinia stores, VueUse composables, and Vite for modern reactive apps. It pairs layered technologies for end-to-end type safety and out-of-the-box deploys, fitting everything from MVPs to production SaaS.

How do I spin up a working demo with Vue 3 Composition API Patterns in 10 minutes?

Two steps: (1) Scaffold — npm create vue@latest, select TypeScript + Pinia + Router; (2) Setup syntax — <script setup lang="ts">, no boilerplate return statement. Get the local dev server running, then wire one real data source to verify the end-to-end loop.

What is the most common pitfall with Vue 3 Composition API Patterns and how do I avoid it?

The most common pitfall is: Destructuring reactive object loses reactivity — use toRefs() or storeToRefs() for Pinia. Avoid it by adding the matching checklist to your PR template and running type-check + lint + unit tests in CI — three gates before merge.

What are the best practices for Vue 3 Composition API Patterns?

Best practices for Vue 3 Composition API Patterns include: Use <script setup> — 30% less boilerplate, better tree-shaking, TS inference; Composables over mixins — named imports, no property collisions, tree-shakeable; Pinia setup stores — function syntax, full TS, use computed for getters. The first one — "Use <script setup> — 30% less boilerplate, better tree-shaking, TS inference" — should be set up at project init to avoid costly rework later.

When should I NOT choose Vue 3 Composition API Patterns?

Pick something else in three cases: (1) the team has zero experience with the core framework and the deadline is tight (learning-curve risk); (2) it's a pure content/marketing site (Astro is lighter); (3) you need very high throughput (>10k RPS) or strict-consistency microservices (Go/Rust). Vue 3 Composition API Patterns shines for mid-to-high complexity full-stack and API work — don't over-engineer simple static pages with it.