typescript 如何声明两个数字元组的返回类型？
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How do I declare a return type of a tuple of two numbers?
提问by ave
When I declare a function as
当我将函数声明为
const coordinates = (id: number): ([number, number]) => {
the error I get is [ts] Duplicate identifier 'number'.
我得到的错误是 [ts] Duplicate identifier 'number'.
If I omit type signature for return value, then it infers it as number[]
如果我省略返回值的类型签名，那么它会将其推断为 number[]
回答by Tom Cumming
const coordinates = (id: number): [number, number] => [id, id];
No need for the parenthesis around the return tuple type
不需要围绕返回元组类型的括号
回答by Alexandre Hitchcox
const coordinates = (id: number) => [id, id] as const;
// const coordinates: (id: number) => [number, number]
From TypeScript 3.4 onwards you can use const assertations.
从 TypeScript 3.4 开始，您可以使用 const 断言。
