Typescript - Component's property types are not correct

[AntoineEsteve]

Version

Vuejs: 2.5.16
Typescript: 2.8.1

Reproduction link

https://stackblitz.com/edit/typescript-rrnw8z?file=index.ts

Steps to reproduce

• Use typescript
• Create a component with at least one property

What is expected?

If your property of type X is not required, its type should be X | undefined

What is actually happening?

If your property of type X is not required, its type is still X

---

More dangerous: The properties are not required by default and you can easily write code that will fail at runtime.

Note: The stackblitz above won't show the error because the types are not correctly assumed and this is assumed as any

[KaelWD]

#6901 (comment)

[ChuChencheng]

Will this issue be fixed in Vue 3.x ?
Or how to correct it with TS 3.4+ ? 😕