如何在 TypeScript 中声明一个固定长度的数组 [英] How to declare a Fixed length Array in TypeScript

问题描述

冒着证明我对 TypeScript 类型缺乏了解的风险 - 我有以下问题.

At the risk of demonstrating my lack of knowledge surrounding TypeScript types - I have the following question.

当你为这样的数组进行类型声明时...

When you make a type declaration for an array like this...

position: Array<number>;

...它会让你制作一个任意长度的数组.但是，如果您想要一个包含特定长度数字的数组，即 x,y,z 分量为 3，您可以为固定长度数组创建一个类型，例如这样吗?

...it will let you make an array with arbitrary length. However, if you want an array containing numbers with a specific length i.e. 3 for x,y,z components can you make a type with for a fixed length array, something like this?

position: Array<3>

感谢任何帮助或澄清！

推荐答案

javascript 数组有一个接受数组长度的构造函数:

The javascript array has a constructor that accepts the length of the array:

let arr = new Array<number>(3);
console.log(arr); // [undefined × 3]

然而，这只是初始大小，改变它没有限制:

However, this is just the initial size, there's no restriction on changing that:

arr.push(5);
console.log(arr); // [undefined × 3, 5]

Typescript 具有 元组类型，可让您定义数组具有特定长度和类型:

Typescript has tuple types which let you define an array with a specific length and types:

let arr: [number, number, number];

arr = [1, 2, 3]; // ok
arr = [1, 2]; // Type '[number, number]' is not assignable to type '[number, number, number]'
arr = [1, 2, "3"]; // Type '[number, number, string]' is not assignable to type '[number, number, number]'

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