Object shapes

Required

Removes `?` from every property, one level deep.

What it is

The mirror of `Partial`, written with `-?`. The minus sign is the whole mechanism: modifiers in a mapped type can be added with `+?` and removed with `-?`, and `Required` is the standard library using the second. It also strips `undefined` from the property type, which is a separate effect people rarely expect.

Examples

```
Required<{ a?: string; b?: number }>
```
→{ a: string; b: number; }
```
Required<{ a?: string | undefined }>
```
→{ a: string; }
`undefined` goes too — `-?` removes it from the type, not only the `?` from the key.
```
Required<{ a: string }>
```
→{ a: string; }

Each resolved type above was printed by TypeScript 5.9.3, not written by hand.

What it does not do

It does not make a property non-null. `Required<{ a?: string | null }>` still has `null` in it — only `undefined` is removed.
It is not deep either. The symmetry with `Partial` holds all the way to the limitation.

Takeaway

`-?` does two things at once: it removes the optionality and it removes `undefined`. Most confusion about `Required` is the second one arriving unannounced.