问题

抱歉，代码部分不会被翻译。以下是翻译好的部分：

"Hi everyone I'm trying to create an interface for my function. The objective is that if the value of action is edit I want to have an indexToEdit else this parameter should be undefined or not mentioned. I don't think it's possible the way I tried it.

It's why I tried another solution.

I would like to find a clean way to do it.

Thanks for your answers."

interface IManageActions {
  action: "add" | "remove" | "edit";
  element: AddExtra;
  list: AddExtra[];
  indextoEdit: typeof action extends "edit" ? number : undefined;
}

interface IManageActions {
  action: "add" | "remove" | "edit";
  element: AddExtra;
  list: AddExtra[];
}
interface IManageActionsEdit {
  action: "edit";
  element: AddExtra;
  list: AddExtra[];
  indextoEdit: number;
}

function manageActions({
  action,
  element,
  list,
  indextoEdit,
}: IManageActions | IManageActionsEdit){}

答案1

得分: 0

以下是您要翻译的内容：

您正在寻找一个[distributive union type](https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#distributive-conditional-types)。让我们首先提取共同的字段：

type CommonFields = { element: AddExtra; list: AddExtra[] }

现在，让我们创建整个类型，在 action: 'edit' 时才提到 indexToEdit：

type IManageActions = CommonFields & (
  | {
    action: 'edit';
    indexToEdit: number;
  }
  | {
    action: 'add' | 'remove';
  }
)

然而，这种方式仍然无法访问 indexToEdit，因为它在变体中不存在。解决方法是将 indexToEdit 添加到另一种变体中，并将其设置为类型 never 的可选项：

type AddExtra = {};

type CommonFields = { element: AddExtra; list: AddExtra[] }

type IManageActions = CommonFields & (
  | {
    action: 'edit';
    indexToEdit: number;
  }
  | {
    action: 'add' | 'remove';
    indexToEdit?: never;
  }
);

playground

<details>
<summary>英文:</summary>

You are looking for a [distributive union type](https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#distributive-conditional-types). Let&#39;s extract the common fields first:

type CommonFields = { element: AddExtra; list: AddExtra[] }

Now, let's create the whole type, where the `indexToEdit` will be only mentioned where the `action: 'edit'`:

type IManageActions = CommonFields & (
| {
action: 'edit';
indextoEdit: number;
}
| {
action: 'add' | 'remove';
}
)

However, this way `indextoEdit` still won't be accessible because it doesn't exist in the variations. The solution would be to add the `indexToEdit` to the other variant and make it optional with of type `never`:

type AddExtra = {};

type CommonFields = { element: AddExtra; list: AddExtra[] }

type IManageActions = CommonFields & (
| {
action: 'edit';
indextoEdit: number;
}
| {
action: 'add' | 'remove';
indextoEdit?: never;
}
);

[playground](https://www.typescriptlang.org/play?ts=5.0.4#code/C4TwDgpgBAggJnAogD2AJwIZQLxQN4C+A3AFAmiRQDCA9gLZ00B2AYgJYQA2cAzjvlC4Q6EJsABcsBCnQYiUTmx4SpSVJgDaAXSgEyFaAEkAshiYYA5hBgBjYG2Z9ctBs3ZdeUAGRQAFCSgoAB98AMCoDDsHJkkAcgg4NmBY0nCoNiY4CFQaRESVJgBXOgAjCDRU3TCQvDDAyPtmOIwEWOCoWLRhGgA3CBS69Mzs4Fz8gH5JJgg+irC9AEpSIA)




</details>