Why Vue 3 Composition API Changes Everything

Vue 3's Composition API coupled with <script setup> drastically reduces code verbosity compared to the legacy Options API. It enables seamless code organization by logical feature rather than component lifecycle hooks.

Understanding Reactivity Primitives: ref vs reactive

Choosing between ref() for primitive values and reactive() for complex nested objects is essential for clean state management:

<script setup>
import { ref, reactive, computed } from 'vue';

const searchQuery = ref('');
const state = reactive({
  items: [],
  isLoading: false,
});

const filteredItems = computed(() => {
  return state.items.filter(item => 
    item.name.toLowerCase().includes(searchQuery.value.toLowerCase())
  );
});
</script>

<template>
  <div class="search-container">
    <input v-model="searchQuery" placeholder="Search components..." />
    <ul>
      <li v-for="item in filteredItems" :key="item.id">{{ item.name }}</li>
    </ul>
  </div>
</template>

By leveraging composables, Vue 3 allows sharing stateful logic across multiple components without mixin collision risks.