我收到有关一个正常工作的TypeScript多维数组的警告的原因是什么？

huangapple
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英文:

Why am I getting warnings about a TypeScript multidimensional array that works?

问题

  1. 我有一个存储在多维关联数组中的人员数组。每个人属于一个地方，每个地方属于一个时区。我设置了我的变量如下：
  3. ```typescript
  4. interface AssociativeArray {
  5.     [key: string]: Array<object> | string | number | object;
  6. }
  8. export var mapDB: AssociativeArray[] = [
  9.     {
  10.         timeZone: "HST",
  11.         places: [
  12.             {
  13.                 place: "Oahu",
  14.                 members: ["Frank", "Jerry", "Pearl"],
  15.             },
  16.             {
  17.                 place: "Maui",
  18.                 members: ["Susan", "Liana", "Bertha"],
  19.             },
  20.         ],
  21.     },
  22.     {
  23.         timeZone: "PST",
  24.         places: [
  25.             {
  26.                 place: "Tahiti",
  27.                 members: ["Fido", "Snowy", "Butch"],
  28.             },
  29.         ],
  30.     },
  31. ];

要访问数组中的特定元素，我使用以下代码：

  1. console.log("The name: ", mapDB[0]["places"][1]["members"][2]);

这段代码返回了预期值 "Bertha"。然而，在 VS Code 中，这一行标有错误消息：

  1. Element implicitly has an 'any' type because expression of type '1' can't be used to index type 'string | number | object | object[]'.
  2.   Property '1' does not exist on type 'string | number | object | object[]'

我已经尝试编写不同版本的 "interface"，但似乎无法消除错误消息。有人能帮我修复吗？

  2. <details>
  3. <summary>英文:</summary>
  5. I have an array of people stored in a multidimensional associative array. Each person belongs to a place and each place belongs to a timezone. I set up my variable like this:
  7. ```typescript
  8. interface AssociativeArray {
  9.     [key: string]: Array&lt;object&gt; | string | number | object;
  10. }
  12. export var mapDB: AssociativeArray[] = [
  13.     {
  14.         timeZone: &quot;HST&quot;,
  15.         places: [
  16.             {
  17.                 place: &quot;Oahu&quot;,
  18.                 members: [&quot;Frank&quot;, &quot;Jerry&quot;, &quot;Pearl&quot;],
  19.             },
  20.             {
  21.                 place: &quot;Maui&quot;,
  22.                 members: [&quot;Susan&quot;, &quot;Liana&quot;, &quot;Bertha&quot;],
  23.             },
  24.         ],
  25.     },
  26.     {
  27.         timeZone: &quot;PST&quot;,
  28.         places: [
  29.             {
  30.                 place: &quot;Tahiti&quot;,
  31.                 members: [&quot;Fido&quot;, &quot;Snowy&quot;, &quot;Butch&quot;],
  32.             },
  33.         ],
  34.     },
  35. ];

To access a specific element in the array, I use the following code:

  1. console.log(&quot;The name: &quot;, mapDB[0][&quot;places&quot;][1][&quot;members&quot;][2]);

This code returns the expected value of "Bertha". However, in VS Code, this line is marked with an error message:

  1. Element implicitly has an &#39;any&#39; type because expression of type &#39;1&#39; can&#39;t be used to index type &#39;string | number | object | object[]&#39;.
  2.   Property &#39;1&#39; does not exist on type &#39;string | number | object | object[]&#39;

I have tried to write different versions of the "interface" but I cannot seem to get rid of the error message. Can someone help me fix it?

答案1

得分: 2

错误发生是因为 TypeScript 无法推断多维关联数组中嵌套元素的实际类型。您需要对类型更加具体：

  1. interface Place {
  2.   place: string;
  3.   members: string[];
  4. }
  6. interface TimeZone {
  7.   timeZone: string;
  8.   places: Place[];
  9. }
  11. export const mapDB: TimeZone[] = [
  12.   {
  13.     timeZone: "HST",
  14.     places: [
  15.       {
  16.         place: "Oahu",
  17.         members: ["Frank", "Jerry", "Pearl"],
  18.       },
  19.       {
  20.         place: "Maui",
  21.         members: ["Susan", "Liana", "Bertha"],
  22.       },
  23.     ],
  24.   },
  25.   {
  26.     timeZone: "PST",
  27.     places: [
  28.       {
  29.         place: "Tahiti",
  30.         members: ["Fido", "Snowy", "Butch"],
  31.       },
  32.     ],
  33.   },
  34. ];
英文:

The error happens because TypeScript cannot infer the actual types of the nested elements in the multidimensional associative array. You need to be more specific with the types:

  1. interface Place {
  2.   place: string;
  3.   members: string[];
  4. }
  6. interface TimeZone {
  7.   timeZone: string;
  8.   places: Place[];
  9. }
  11. export const mapDB: TimeZone[] = [
  12.   {
  13.     timeZone: &quot;HST&quot;,
  14.     places: [
  15.       {
  16.         place: &quot;Oahu&quot;,
  17.         members: [&quot;Frank&quot;, &quot;Jerry&quot;, &quot;Pearl&quot;],
  18.       },
  19.       {
  20.         place: &quot;Maui&quot;,
  21.         members: [&quot;Susan&quot;, &quot;Liana&quot;, &quot;Bertha&quot;],
  22.       },
  23.     ],
  24.   },
  25.   {
  26.     timeZone: &quot;PST&quot;,
  27.     places: [
  28.       {
  29.         place: &quot;Tahiti&quot;,
  30.         members: [&quot;Fido&quot;, &quot;Snowy&quot;, &quot;Butch&quot;],
  31.       },
  32.     ],
  33.   },
  34. ];

huangapple
  • 本文由 发表于 2023年6月16日 13:28:16
  • 转载请务必保留本文链接：https://go.coder-hub.com/76487183.html
  • arrays
  • associative-array
  • javascript
  • reactjs
  • typescript
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