Vue 3 + Typescript + Vite

• defineProps withDefaults

import { PropType, withDefaults, defineProps } from 'vue'
import type { ExtractPropTypes } from 'vue'

// 法一
type TestProps = {
  name: string
  age?: number
}

const props = withDefaults(defineProps<TestProps>(), {
  name: '',
  age: 18
})

// 法二
withDefaults(defineProps<{ name: string; age?: number }>(), {
  name: 'hello vite',
  age: 18
})

// 法三 类型反推

const treeProps = {
  data: {
    type: Array as PropType<string[]>,
    default: () => []
  }
}

type TreeProps = ExtractPropTypes<typeof treeProps>

• defineEmits

export const alertEmits = {
  close: (evt: MouseEvent) => evt instanceof MouseEvent
}
export type AlertEmits = typeof alertEmits

const emit = defineEmits(alertEmits)

• defineExpose