Typescript v3.9 introduces the @ts-expect-error assertion added to TypeScript 3.9. This assertion is more descriptive than @ts-ignore because, rather than just ignoring the next line, it is explicitly ignoring a compiler error.

// @ts-expect-error
const num: number = 'hello'
// @ts-ignore
const num2: number = 'hello

Both will work.

If change to:

ts-expect-error: means that this should have error, but I want to ingore it. if it compile correctly, then it report a error.

If this is not longer be an error, means that something has been changed.

It can help if the types is defined in another file, it was modified without benn notified