Vue

> Based on Vue 3.5. Always use Composition API with <script setup lang="ts">.

Preferences

• Prefer TypeScript over JavaScript
• Prefer <script setup lang="ts"> over <script>
• For performance, prefer shallowRef over ref if deep reactivity is not needed
• Always use Composition API over Options API
• Discourage using Reactive Props Destructure

Core

| Topic | Description | Reference | |-------|-------------|-----------| | Script Setup & Macros | <script setup>, defineProps, defineEmits, defineModel, defineExpose, defineOptions, defineSlots, generics | script-setup-macros | | Reactivity & Lifecycle | ref, shallowRef, computed, watch, watchEffect, effectScope, lifecycle hooks, composables | core-new-apis |

Features

| Topic | Description | Reference | |-------|-------------|-----------| | Built-in Components & Directives | Transition, Teleport, Suspense, KeepAlive, v-memo, custom directives | advanced-patterns |

Quick Reference

Component Template

vue
<script setup lang="ts">
import { ref, computed, watch, onMounted } from 'vue'

const props = defineProps<{
  title: string
  count?: number
}>()

const emit = defineEmits<{
  update: [value: string]
}>()

const model = defineModel<string>()

const doubled = computed(() => (props.count ?? 0) * 2)

watch(() => props.title, (newVal) => {
  console.log('Title changed:', newVal)
})

onMounted(() => {
  console.log('Component mounted')
})
</script>

<template>
  <div>{{ title }} - {{ doubled }}</div>
</template>

Key Imports

ts
// Reactivity
import { ref, shallowRef, computed, reactive, readonly, toRef, toRefs, toValue } from 'vue'

// Watchers
import { watch, watchEffect, watchPostEffect, onWatcherCleanup } from 'vue'

// Lifecycle
import { onMounted, onUpdated, onUnmounted, onBeforeMount, onBeforeUpdate, onBeforeUnmount } from 'vue'

// Utilities
import { nextTick, defineComponent, defineAsyncComponent } from 'vue'