> For the complete documentation index, see [llms.txt](https://docs.superstructjs.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.superstructjs.org/api-reference/typescript.md).
# TypeScript
Superstruct is designed with TypeScript in mind, so that you don't need to duplicate type definitions.
## Utilities
### `Describe`
The `Describe` utility returns a type representing a struct for a given valid value type. This allows you to ensure you're writing your struct definitions properly, for example:
```ts
type User = {
id: number
name: string
}
const User: Describe = object({
id: string(), // This mistake will fail to pass type checking!
name: string(),
})
```
> 🤖 There are limitations to what `Describe` can do, specifically it will always assume object types are as strict as possible. So describing the `type()` struct is not possible, and simple unions of strings will be required to use `enums()`.
### `Infer`
The `Infer` utility type extracts the type of a valid value from a struct definition. This allows you to avoid having to duplicate effort when writing typings, for example:
```ts
const User = object({
id: number(),
name: string(),
})
type User = Infer
// type User = {
// id: number
// name: string
// }
```
> 🤖 If you are not using TypeScript's [`strictNullChecks`](https://www.typescriptlang.org/tsconfig#strictNullChecks) option, Superstruct will be unable to infer your "optional" types correctly and will mark all types as optional.