> For the complete documentation index, see [llms.txt](https://mm.ricky.moe/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mm.ricky.moe/javascript/typescript/shi-yong/required.md).

# Required

```typescript
type Required<T> = { [P in keyof T]-?: T[P] };
```

我们发现一个有意思的用法 `-?`, 这里很好理解就是将可选项代表的 `?` 去掉, 从而让这个类型变成必选项. 与之对应的还有个`+?` , 这个含义自然与`-?`之前相反, 它是用来把属性变成可选项的.


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