Vue3.3.1+TS 全新使用指南

Vue3.3.1相对于Vue3.2.47在Typescript方面主要有两点变化：1. defineProps类型支持外部导入；2.defineEmits提供了更简便的声明方式

ref

传入一个泛型参数

• 值 ref

const initCode = ref('200'); //默认推导出string类型

//或者手动定义更复杂的类型
const initCode = ref<string | number>('200');

• 模板 ref

<template>
  <div ref="el"></div>
</template>


<script setup lang="ts">
import { ref } from 'vue';
const el = ref<HTMLDivElement| null>(null);
</script>

• 组件 ref

<template>
  <HelloWorld ref="helloworld" />
</template>


<script setup lang="ts">
import { ref, onMounted } from 'vue';
import HelloWorld from '@/components/HelloWorld.vue';


const helloworld = ref<InstanceType<typeof HelloWorld> | null>(null);


onMounted(() => {
  //调用子组件的handleClick方法
  helloworld.value?.handleClick();
});
</script>

如果子组件使用<script setup lang="ts">，默认是全关闭的，子组件需使用defineExpose定义父组件能访问的属性

reactive

• 定义接口

新建src/types/user.ts（在types文件夹下新建user.ts）

export interface User {
  name: string;
  age: number;
}

• 使用

<script setup lang="ts">
import { reactive } from 'vue';
import type { User } from '@/types/user';


//reactive 会隐式地从它的参数中推导类型
//也可以使用接口直接给变量定义类型
const user: User = reactive({
  name: 'zhangsan',
  age: 20,
});
</script>

提示：不推荐使用 reactive() 的泛型参数，因为处理了深层次 ref 解包的返回值与泛型参数的类型不同

computed

computed() 会自动从其计算函数的返回值上推导出类型

也可以通过泛型参数显式指定类型

const age = computed<number>(() => {
  return 2;
});

defineProps（父传子）

定义props类型，直接使用，不需要import引入

• 基本使用

传入泛型参数

<script setup lang="ts">
//使用外部导入的类型
import type { User } from "@/types/user";

const props = defineProps<User>();

console.log(props.name);
</script>

• 定义默认值

使用 withDefaults 定义默认值

<script setup lang="ts">
//使用外部导入的类型
import type { User } from "@/types/user";

const props = withDefaults(defineProps<User>(), {
  name: "hello",
  age: 10,
});

console.log(props.name);
</script>

defineEmits（子传父）

定义emits类型 ，直接使用，不需要import引入

父组件

<template>
  <div>
    <HelloWorld @change="handleChange" />
  </div>
</template>

<script setup lang="ts">
import HelloWorld from "@/components/HelloWorld.vue";
import type { User } from "@/types/user";
const handleChange = (value: User) => {
  console.log(value);
};
</script>

子组件

<template>
  <div>
    <button @click="handleClick">按钮</button>
  </div>
</template>

<script setup lang="ts">
import type { User } from "@/types/user";
const emit = defineEmits<{ change: [value: User] }>();

const handleClick = () => {
  emit("change", { name: "2", age: 21 });
};
</script>

defineExpose（父调用子）

定义父组件通过模板 ref 能获取到的属性

接着上面组件ref案例修改子组件HelloWorld

<template>
  <div></div>
</template>

<script setup lang="ts">
const handleClick = () => {
  console.log('子组件方法');
};
defineExpose({ handleClick });
</script>

defineSlots

定义作用域插槽参数类型

<!-- 父组件 -->
<template>
  <div>
    <HelloWorld>
      <template #="{ msg }"> {{ msg }} </template>
    </HelloWorld>
  </div>
</template>

<script lang="ts" setup>
import HelloWorld from "./components/HelloWorld.vue";
</script>

<!-- 子组件 -->
<template>
  <h1>
    <slot msg="12"></slot>
  </h1>
</template>

<script setup lang="ts">
defineSlots<{
  default(props: { msg: string }): any
}>()
</script>

provide / inject（跨组件传值）

• key是Symbol

新建src/constant/index.ts

import type { InjectionKey } from 'vue';

export const key = Symbol() as InjectionKey<string>;

<!-- 父组件使用provide提供值 -->
<script setup lang="ts">
import { provide } from 'vue';
import { key } from '@/constant/index';
provide(key, '123'); //提供改变响应式对象的方法
</script>

<!-- 子组件使用inject取值 -->
<script setup lang="ts">
import { inject } from 'vue';
import { key } from '@/constant/index';
const string = inject(key);
</script>

• key是字符串

inject返回的类型是 unknown，需要通过泛型参数显式声明

<!-- 父组件提供provide -->
<script setup lang="ts">
import { ref, provide } from 'vue';
const state = ref(0);
const handlerState = () => {
  state.value = 1;
};
provide('info', state); //提供响应式对象
provide('func', handlerState); //提供改变响应式对象的方法
</script>

<!-- 子组件使用inject取值 -->
<script setup lang="ts">
import { inject } from 'vue';

//通过泛型参数显式声明
const state = inject<number>('info');
const func = inject<() => void>('func');
</script>

• undefined问题

由于无法保证provide会提供这个值，因此inject通过泛型参数显示声明了类型，还会多个undefined类型

提供默认值，可消除undefined

const state = inject<number>('info', 20);

使用类型断言，告诉编辑器这个值一定会提供

const state = inject('info') as number;

事件类型

input change事件

<template>
  <input type="text" @change="handleChange" />
</template>

<script setup lang="ts">
const handleChange = (evt: Event) => {
  console.log((evt.target as HTMLInputElement).value);
};
</script>

• button Click事件

<template>
  <button @click="handleClick">按钮</button>
</template>

<script setup lang="ts">
const handleClick = (evt: Event) => {
  //获取按钮的样式信息
  console.log((evt.target as HTMLButtonElement).style);
};
</script>

• HTML标签映射关系

interface HTMLElementTagNameMap {
  "a": HTMLAnchorElement;
  "abbr": HTMLElement;
  "address": HTMLElement;
  "applet": HTMLAppletElement;
  "area": HTMLAreaElement;
  "article": HTMLElement;
  "aside": HTMLElement;
  "audio": HTMLAudioElement;
  "b": HTMLElement;
  "base": HTMLBaseElement;
  "basefont": HTMLBaseFontElement;
  "bdi": HTMLElement;
  "bdo": HTMLElement;
  "blockquote": HTMLQuoteElement;
  "body": HTMLBodyElement;
  "br": HTMLBRElement;
  "button": HTMLButtonElement;
  "canvas": HTMLCanvasElement;
  "caption": HTMLTableCaptionElement;
  "cite": HTMLElement;
  "code": HTMLElement;
  "col": HTMLTableColElement;
  "colgroup": HTMLTableColElement;
  "data": HTMLDataElement;
  "datalist": HTMLDataListElement;
  "dd": HTMLElement;
  "del": HTMLModElement;
  "details": HTMLDetailsElement;
  "dfn": HTMLElement;
  "dialog": HTMLDialogElement;
  "dir": HTMLDirectoryElement;
  "div": HTMLDivElement;
  "dl": HTMLDListElement;
  "dt": HTMLElement;
  "em": HTMLElement;
  "embed": HTMLEmbedElement;
  "fieldset": HTMLFieldSetElement;
  "figcaption": HTMLElement;
  "figure": HTMLElement;
  "font": HTMLFontElement;
  "footer": HTMLElement;
  "form": HTMLFormElement;
  "frame": HTMLFrameElement;
  "frameset": HTMLFrameSetElement;
  "h1": HTMLHeadingElement;
  "h2": HTMLHeadingElement;
  "h3": HTMLHeadingElement;
  "h4": HTMLHeadingElement;
  "h5": HTMLHeadingElement;
  "h6": HTMLHeadingElement;
  "head": HTMLHeadElement;
  "header": HTMLElement;
  "hgroup": HTMLElement;
  "hr": HTMLHRElement;
  "html": HTMLHtmlElement;
  "i": HTMLElement;
  "iframe": HTMLIFrameElement;
  "img": HTMLImageElement;
  "input": HTMLInputElement;
  "ins": HTMLModElement;
  "kbd": HTMLElement;
  "label": HTMLLabelElement;
  "legend": HTMLLegendElement;
  "li": HTMLLIElement;
  "link": HTMLLinkElement;
  "main": HTMLElement;
  "map": HTMLMapElement;
  "mark": HTMLElement;
  "marquee": HTMLMarqueeElement;
  "menu": HTMLMenuElement;
  "meta": HTMLMetaElement;
  "meter": HTMLMeterElement;
  "nav": HTMLElement;
  "noscript": HTMLElement;
  "object": HTMLObjectElement;
  "ol": HTMLOListElement;
  "optgroup": HTMLOptGroupElement;
  "option": HTMLOptionElement;
  "output": HTMLOutputElement;
  "p": HTMLParagraphElement;
  "param": HTMLParamElement;
  "picture": HTMLPictureElement;
  "pre": HTMLPreElement;
  "progress": HTMLProgressElement;
  "q": HTMLQuoteElement;
  "rp": HTMLElement;
  "rt": HTMLElement;
  "ruby": HTMLElement;
  "s": HTMLElement;
  "samp": HTMLElement;
  "script": HTMLScriptElement;
  "section": HTMLElement;
  "select": HTMLSelectElement;
  "slot": HTMLSlotElement;
  "small": HTMLElement;
  "source": HTMLSourceElement;
  "span": HTMLSpanElement;
  "strong": HTMLElement;
  "style": HTMLStyleElement;
  "sub": HTMLElement;
  "summary": HTMLElement;
  "sup": HTMLElement;
  "table": HTMLTableElement;
  "tbody": HTMLTableSectionElement;
  "td": HTMLTableDataCellElement;
  "template": HTMLTemplateElement;
  "textarea": HTMLTextAreaElement;
  "tfoot": HTMLTableSectionElement;
  "th": HTMLTableHeaderCellElement;
  "thead": HTMLTableSectionElement;
  "time": HTMLTimeElement;
  "title": HTMLTitleElement;
  "tr": HTMLTableRowElement;
  "track": HTMLTrackElement;
  "u": HTMLElement;
  "ul": HTMLUListElement;
  "var": HTMLElement;
  "video": HTMLVideoElement;
  "wbr": HTMLElement;
}

结尾

vue3.3还新增了defineModel(实验特性)。这个API因使用情景罕见，所以没有在本篇文章介绍，有兴趣的可自行去官网了解