如何解决 TypeScript 中的错误？

huangapple
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英文:

How can I solve errors in TypeScript?

问题

  1. 我是TypeScript新手。以下是我的代码，其中在注释中提到了错误。出了什么问题？

type BooleanAttributeName = string;
type PairedAttribute = {
[_: string]: string | number;
};
type CompositeAttribute = [
PairedAttribute,
BooleanAttributeName | BooleanAttributeName[]
];
type Attributes = CompositeAttribute | PairedAttribute;

function SetAttributes(attributes: Attributes) {
if (attributes.length === undefined) {
for (const key in attributes) {
console.log(key, attributes[key]); /错误：因为类型为 'Attributes' 的表达式不能用于索引类型为 'string' 的表达式，所以元素隐含地具有 'any' 类型。在类型 'Attributes' 上找不到具有参数类型 'string' 的索引签名。/
}
}
attributes.map((item) => { /此表达式不可调用。'string | number | ((callbackfn: (value: string | PairedAttribute | string[], index: number, array: (string | PairedAttribute | string[])[]) => U, thisArg?: any) => U[])' 的所有成员都不可调用。类型 'string' 没有调用签名。/ /参数 'item' 隐式具有 'any' 类型。/
if (item.length === undefined) {
for (const key in item) {
console.log(key, item[key]);
}
} else if (typeof item === "object") {
item.map((BooleanAttributeName) => { /参数 'BooleanAttributeName' 隐式具有 'any' 类型。/
console.log(BooleanAttributeName);
});
} else {
console.log(item);
}
});
}

let sample: Attributes = [
{
key1: "value1",
key2: "value2",
},
["BooleanAttribute1", "BooleanAttribute2"],
];

SetAttributes(sample);

  2. 我尝试使用了[官方TypeScript文档](https://www.typescriptlang.org/docs/handbook/2/narrowing.html)中的一些缩小类型的概念，但仍然遇到了这些问题。
  4. 我想知道如何解决这个问题的解决方案。
英文:

I'm new to TypeScript. Below is my code with errors mentioned in comments. What is going wrong?

  1. type BooleanAttributeName = string;
  2. type PairedAttribute = {
  3.     [_: string]: string | number;
  4. };
  5. type CompositeAttribute = [
  6.     PairedAttribute,
  7.     BooleanAttributeName | BooleanAttributeName[]
  8. ];
  9. type Attributes = CompositeAttribute | PairedAttribute;
  11. function SetAttributes(attributes: Attributes) {
  12.     if (attributes.length === undefined) {
  13.         for (const key in attributes) {
  14.             console.log(key, attributes[key]); /*Error: Element implicitly has an 'any' type because expression of type 'string' can't be used to index type 'Attributes'. No index signature with a parameter of type 'string' was found on type 'Attributes'.*/
  15.         }
  16.     }
  17.     attributes.map((item) => { /*This expression is not callable. Not all constituents of type 'string | number | (<U>(callbackfn: (value: string | PairedAttribute | string[], index: number, array: (string | PairedAttribute | string[])[]) => U, thisArg?: any) => U[])' are callable. Type 'string' has no call signatures.*/ /*Parameter 'item' implicitly has an 'any' type.*/
  18.         if (item.length === undefined) {
  19.             for (const key in item) {
  20.                 console.log(key, item[key]);
  21.             }
  22.         } else if (typeof item === "object") {
  23.             item.map((BooleanAttributeName) => { /*Parameter 'BooleanAttributeName' implicitly has an 'any' type.*/
  24.                 console.log(BooleanAttributeName);
  25.             });
  26.         } else {
  27.             console.log(item);
  28.         }
  29.     });
  30. }
  32. let sample: Attributes = [
  33.     {
  34.         key1: "value1",
  35.         key2: "value2",
  36.     },
  37.     ["BooleanAttribute1", "BooleanAttribute2"],
  38. ];
  40. SetAttributes(sample);

I tried to use some concepts of narrowing from the official TypeScript docs but still I am facing these problems.

I want to know what can be solution for the problem.

答案1

得分: 1

尝试添加一些类型转换和检查：

  1. type BooleanAttributeName = string;
  2. type PairedAttribute = {
  3.   [_: string]: string | number;
  4. };
  5. type CompositeAttribute = [
  6.   PairedAttribute,
  7.   BooleanAttributeName | BooleanAttributeName[]
  8. ];
  9. type Attributes = CompositeAttribute | PairedAttribute;
  11. function SetAttributes(attributes: Attributes) {
  12.   if (typeof attributes === 'object') {
  13.     const attr = attributes as PairedAttribute;
  14.     for (const key in attr) {
  15.       console.log(key, attr[key]); 
  16.     }
  17.   }
  18.   if (attributes instanceof Array) {
  19.     const attr = attributes as CompositeAttribute;
  20.     attr.map((item) => {
  21.       if (typeof item === "object") {
  22.         const it = item as PairedAttribute;
  23.         for (const key in it) {
  24.           console.log(key, it[key]);
  25.         }
  26.       } else {
  27.         console.log(item);
  28.       }
  29.     });
  30.   }
  31. }
  33. let sample: Attributes = [
  34.   {
  35.     key1: "value1",
  36.     key2: "value2",
  37.   },
  38.   ["BooleanAttribute1", "BooleanAttribute2"],
  39. ];
  41. SetAttributes(sample);

链接到 Playground

英文:

Try to add some type casting and checking:

  1. type BooleanAttributeName = string;
  2. type PairedAttribute = {
  3.   [_: string]: string | number;
  4. };
  5. type CompositeAttribute = [
  6.   PairedAttribute,
  7.   BooleanAttributeName | BooleanAttributeName[]
  8. ];
  9. type Attributes = CompositeAttribute | PairedAttribute;
  11. function SetAttributes(attributes: Attributes) {
  12.   if (typeof attributes === 'object') {
  13.     const attr = attributes as PairedAttribute;
  14.     for (const key in attr) {
  15.       console.log(key, attr[key]); 
  16.     }
  17.   }
  18.   if (attributes instanceof Array) {
  19.     const attr = attributes as CompositeAttribute;
  20.     attr.map((item) => {
  21.       if (typeof item === "object") {
  22.         const it = item as PairedAttribute;
  23.         for (const key in it) {
  24.           console.log(key, it[key]);
  25.         }
  26.       } else {
  27.         console.log(item);
  28.       }
  29.     });
  30.   }
  31. }
  33. let sample: Attributes = [
  34.   {
  35.     key1: "value1",
  36.     key2: "value2",
  37.   },
  38.   ["BooleanAttribute1", "BooleanAttribute2"],
  39. ];
  41. SetAttributes(sample);

Link to playground

huangapple
  • 本文由 发表于 2023年1月9日 15:50:36
  • 转载请务必保留本文链接：https://go.coder-hub.com/75054395.html
  • typescript
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