无法推送到 UnionType 数组

发布于 2025-01-16 22:07:07 字数 605 浏览 2 评论 0原文

我正在 TS 中使用 UnionTypes，我认为我可以创建一个可以使用它们的有效场景，但我不明白为什么会出现以下错误：

类型参数 '{ name: string; }' 不可分配给类型为 'string & 的参数{ 名称：字符串； }'

知道“强制”这种特定方法的方法，但我想了解为什么这不起作用。

let newArray: string[] | { name: string }[] = new Array();

//just a boolean to know when is one type or the other
    if (isMultiple) {
      otherArray.forEach((item: { name: string }) => {
        newArray.push(item)
      })
    }
    else {
      otherArray.forEach((item: { name: string }) => {
        newArray.push(item.name)
      });
    }

    return newArray

原文

I am playing around with UnionTypes in TS and I thought that I could create a valid scenario where they could be used, but I do not understand why this is breaking with the error of:

Argument of type '{ name: string; }' is not assignable to parameter of type 'string & { name: string; }'

I know ways to "force" this partical approach, but I want to understand why this does not work.

let newArray: string[] | { name: string }[] = new Array();

//just a boolean to know when is one type or the other
    if (isMultiple) {
      otherArray.forEach((item: { name: string }) => {
        newArray.push(item)
      })
    }
    else {
      otherArray.forEach((item: { name: string }) => {
        newArray.push(item.name)
      });
    }

    return newArray

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蓝梦月影 2025-01-23 22:07:07

您不能同时拥有两种类型的数组。您可以执行此操作并定义它，然后在 if 语句中单独创建它

let newArray: string[] | { name: string }[];

//just a boolean to know when is one type or the other
    if (isMultiple) {
      newArray = new Array< { name : string }>();
      otherArray.forEach((item: { name: string }) => {
        newArray.push(item)
      })
    }
    else {
      newArray = new Array<string>();
      otherArrayforEach((item: { name: string }) => {
        newArray.push(item.name)
      });
    }

    return newArray

You cant have both types of arrays at the same time. You could do this and define it then create it separately in the if statement

let newArray: string[] | { name: string }[];

//just a boolean to know when is one type or the other
    if (isMultiple) {
      newArray = new Array< { name : string }>();
      otherArray.forEach((item: { name: string }) => {
        newArray.push(item)
      })
    }
    else {
      newArray = new Array<string>();
      otherArrayforEach((item: { name: string }) => {
        newArray.push(item.name)
      });
    }

    return newArray

回复收藏 0 原文

半窗疏影 2025-01-23 22:07:07

除非你想允许混合数组（let newArray: (string | { name: string })[]），你可以使用

// just a boolean to know when is one type or the other
if (isMultiple) {
  const newArray: { name: string }[] = [];
  otherArray.forEach((item: { name: string }) => {
    newArray.push(item)
  });
  return newArray;
} else {
  const newArray: string[] = [];
  otherArray.forEach((item: { name: string }) => {
    newArray.push(item.name)
  });
  return newArray;
}

Unless you want to allow mixed arrays (let newArray: (string | { name: string })[]), you can use

// just a boolean to know when is one type or the other
if (isMultiple) {
  const newArray: { name: string }[] = [];
  otherArray.forEach((item: { name: string }) => {
    newArray.push(item)
  });
  return newArray;
} else {
  const newArray: string[] = [];
  otherArray.forEach((item: { name: string }) => {
    newArray.push(item.name)
  });
  return newArray;
}

回复收藏 0 原文

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