一文详解Vue3中的script setup语法糖

<script setup>
</script>

<template>
	<Child />
</template>

<script setup>
import Child from '@/components/Child.vue'
</script>

<script setup>
  import { defineProps } from 'vue'

  const props = defineProps({
    title: String,
  })
</script>
<!-- 或者 -->
<script setup> 
    import { ref,defineProps } from 'vue';
    
    type Props={ 
        msg:string 
    }
    defineProps<Props>(); 
</script>

<script setup>
  import { defineEmits } from 'vue'
  const emit = defineEmits(['change', 'delete'])
  
</script>

//父组件
<template>
	<Child @getChild="getChild" :title="msg" />
</template>

<script setup>
import { ref } from 'vue'
import Child from '@/components/Child.vue'
const msg = ref('parent value')
const getChild = (e) => {
	// 接收父组件传递过来的数据
	console.log(e); // child value
}
</script>

//子组件
<template>
	<div @click="toEmits">Child Components</div>
</template>

<script setup>
// defineEmits,defineProps无需导入，直接使用
const emits = defineEmits(['getChild']);
const props = defineProps({
	title: {
		type: String,
		defaule: 'defaule title'
	}
});

const toEmits = () => {
	emits('getChild', 'child value') // 向父组件传递数据
}

// 获取父组件传递过来的数据
console.log(props.title); // parent value
</script>

<template>
    <component v-bind='attrs'></component>
</template>
<class="lazy" data-srcipt setup>
   const attrs = useAttrs();
<script>

// 旧
<script setup>
  import { useContext } from 'vue'

  const { slots, attrs } = useContext()
</script>

// 新
<script setup>
  import { useAttrs, useSlots } from 'vue'

  const attrs = useAttrs()
  const slots = useSlots()
</script>

//子组件

<template>
	{{msg}}
</template>

<script setup>
import { ref } from 'vue'

let msg = ref("Child Components");
let num = ref(123);

// defineExpose无需导入，直接使用
defineExpose({
	msg,
	num
});
</script>

//父组件
<template>
	<Child ref="child" />
</template>

<script setup>
import { ref, onMounted } from 'vue'
import Child from '@/components/Child.vue'

let child = ref(null);

onMounted(() => {
	console.log(child.value.msg); // Child Components
	console.log(child.value.num); // 123
})
</script>

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

const count = ref(0); //不用 return ，直接在 templete 中使用

const addCount=()=>{ //定义函数，使用同上 
    count.value++; 
} 

//创建一个只读的计算属性 ref：
const plusOne = computed(() => count.value + 1)

// 创建一个可写的计算属性 ref
const plusOne = computed({
get: () => count.value + 1, 
set: (val) => { count.value = val - 1 } 
})


//定义监听，使用同上 //...some code else 
watchEffect(()=>console.log(count.value)); 
</script>

<script setup>
import { reactive, onUnmounted } from 'vue'

const state = reactive({
    counter: 0
})
// 定时器 每秒都会更新数据
const timer = setInterval(() => {
    state.counter++
}, 1000);

onUnmounted(() => {
    clearInterval(timer);
})
</script>
<template>
    <div>{{state.counter}}</div>
</template>

export const count = ref(0)

<script setup >
import { ref } from 'vue'

const counter = ref(0);//不用 return ，直接在 templete 中使用

const timer = setInterval(() => {
    counter.value++
}, 1000)

onUnmounted(() => {
    clearInterval(timer);
})
</script>
<template>
    <div>{{counter}}</div>
</template>

<script setup>
  const post = await fetch(`/api/post/1`).then((r) => r.json())
</script>

<script setup>
const post = await fetch(`/api/post/1`).then(r => r.json())
</script>

<script>
// 普通 `<script>`, 在模块范围下执行(只执行一次)
runSideEffectOnce()

// 声明额外的选项
  export default {
    name: "MyComponent",
    inheritAttrs: false,
    customOptions: {}
  }
</script>
<script setup>
    import HelloWorld from '../components/HelloWorld.vue'
    // 在 setup() 作用域中执行 (对每个实例皆如此)
    // your code
</script>
<template>
  <div>
    <HelloWorld msg="Vue3 + TypeScript + Vite"/>
  </div>
</template>