Vue组件的单文件三种写法

用JS对象

export default {data, props, methods, created, ...}

用TS类 <script lang="ts">

@Component
export default class XXX extends Vue{
    xxx: string = 'hi';
@Prop(Number) xxx: number | undefined;
}

用JS类 <script lang="js">

@Component
export default class xxx extends Vue {
    xxx = 'hi'
}