Vue3新的script setup语法糖

/*不使用script-setup语法糖*/
<script>
import { defineComponent } from "vue"
export default defineComponent({
name: 'app',
})
</script>
​
/*使用script-setup语法糖*/
<script setup>
</script>

/*原先*/
<template>
<about />
</template>
<script>
import about from './about.vue'
import { defineComponent } from "vue"
export default defineComponent({
name: 'home',
components: { about }
})
</script>
​
/*用语法糖后*/
<template>
<about />
</template>
<script>
<script setup>
import about from './about.vue'
</script>
组件的引入使用已不再需要components注册才能使用了，直接引入就可以在tamplate使用了，U1S1，这个更改让代码看起来更舒服简介了一些

/*原先*/
<template>
count:{{count}}
num:{{num}}
text:{{text}}
<el-button @click="handleClick">点击</el-button>
</template>
​
<script>
import { reactive, toRefs, ref } from 'vue'
export default {
name: '',
setup() {
/*这里我列举了三种声明变量的方式*/
const count = ref(1)
const num = 2
const state = reactive({
text: "小黄在测试"
})
function handleClick(){
count.value++
}
/*不使用script-srtup语法糖需要导出需要在template使用的变量和方法*/
return { count, num, ...toRefs(state),handleClick }
}
}
</script>
​
/*用语法糖后*/
<template>
count:{{count}}
num:{{num}}
/*这里没有使用toRefs展开变量，所以需要state.text*/
text:{{state.text}}
<el-button @click="handleClick">点击</el-button>
</template>
​
<script setup>
import { reactive, ref } from 'vue'
const count = ref(1)
const num = 2
const state = reactive({
text: "小黄在测试"
})
function handleClick(){
count.value++
}
</script>

使用script setup语法糖后变量和方法已不再需要return出去才能被template使用了，减少了代码量，看起来更加的美观

/*原先*/
/*子组件*/
<template>
{{foo}}
</tamplate>
<script>
import {defineComponent} from 'vue'
export default defineComponent({
name:'son',
props:{
foo:String
}
})
</script>
​
/*父组件*/
<template>
<About foo="我是小黄" />
</template>
<script>
import About from "../about/index.vue"
import {defineComponent} from 'vue'
export default defineComponent({
name:'father',
components:{About}
})
</script>
​
/*用语法糖后*/
/*子组件*/
<template>
{{foo}}
</tamplate>
<script setup>
import {defineProps} from 'vue'
const props = defineProps({
foo:String
})
console.log(props) // Proxy {foo: '我是小黄'}
</script>
/*父组件*/
<template>
<About foo="我是小黄" />
</template>
<script setup>
import About from "../about/index.vue"
</script>

通过 defineProps 指定当前props类型的同时，获得上下文的props对象
在script中需要props[key]引用，而template中可直接调用key
用法上差异不大…

/*原先*/
<template>
<el-button @click="handleClick">点击</el-button>
</template>
<script>
export default{
setup(){
emit:['h-update','h-delete']
}
}
</script>
​
/*用语法糖后*/
<template>
<el-button @click="handleClick">点击</el-button>
</template>
<script setup>
import { defineEmits } from 'vue'
const emit = defineEmits(['h-update', 'h-delete'])
function handleClick(){
emit('h-update')
console.log(emit)
//(event, ...args) => instance.emit(event, ...args)
}
</script>

<script setup>
import {useSlots,useAttrs} from 'vue'
const slots = useSlots()
const attrs = useAttrs()
console.log(slots)//可以获取组件的插槽
console.log(attrs)//可以获取组件的属性
</script>

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

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

<script setup>
  import { directive as clickOutside } from 'v-click-outside'
</script>

<template>
  <div v-click-outside />
</template>

import {defineProps, toRefs,defineEmits,ref} from 'vue' 
const props = defineProps({ isOpen: Boolean })

const count = ref(1)
const obj = ref({
　　count:0
})
console.log(count.value)
console.log(obj.value.count)

const { isOpen } = toRefs(props);