详解vue3中渲染函数的非兼容变更

// 2.0 渲染函数
export default {
 render(h) {
  return h('div')
 }
}

// 3.x语法
export default {
 render() {
  return h('div')
 }
}

// 2.x
export default {
 render(h) {
  return h('div')
 }
}

// 3.x
import { h, reactive } from 'vue'
export default {
 setup(prop, {slots, attrs, emit}) {
  const state = reactive({
   count: 0
  })
  function increment() {
   state.count++
  }
  // 返回render函数
  return () => h(
   'div',
   {
    onClick: increment
   },
   state.count
  )
 }
}

// 2.x
{
 class: ['button', 'is-outlined'],
 style: {color: '#fffff'},
 attr: {id: 'submit'},
 domProps: {innerHTML: ''},
 on: {click: submitForm},
 key: 'submit-button'
}
// 3.x VNode的结构是扁平的
{
 class: ['button', 'is-outlined'],
 style: { color: '#34495E' },
 id: 'submit',
 innerHTML: '',
 onClick: submitForm,
 key: 'submit-button'
}

// 2.x
h(LayoutComponent, [
 h('div', {slot: 'header'}, this.header),
 h('div', {slot: 'header'}, this.header)
])
// 作用域slot：


// 3.x
h(LayoutComponent, {}, {
 header: () => h('div', this.header),
 content: () => h('div', this.content)
})
// 需要以编程方式引入作用域slot时，他们现在被统一在了$slots选项中
// 2.x的作用域slot
this.$scopedSlots.header
// 3.x的写法
this.$slots.header

<template>
<label>
 <input type="text" v-bind="$attrs" v-on="$listeners">
</label>
</template>
<script>
 export default {
  inheritAttrs: false
 }
</script>

<template>
 <label>
  <input type="text" v-bind="$attrs" />
 </label>
</template>
<script>
export default {
 inheritAttrs: false
}
// 如果这个组件接收一个 id attribute 和一个 v-on:close 监听器，那么 $attrs 对象现在将如下所示
{
 id: 'my-input',
 onClose: () => console.log('close Event Triggered')
}
</script>

<template>
 <label>
  <input type="text" v-bind="$attrs" />
 </label>
</template>
<script>
export default {
 inheritAttrs: false
}
</script>
<!-- 写入 -->
<my-component id="my-id" class="my-class"></my-component>
<!-- vue2 将生成 -->
<label class="my-class">
 <input type="text" id="my-id" />
</label>
<!-- vue3 将生成 -->
<label>
 <input type="text" id="my-id" class="my-class" />
</label>