如何使用 TypeScript 键入 N 个字符串数组？

Question

I have an array like this:

const rows: Row[] = [
  [
    1,
    ["breakfast", "apples"],
  ],
  [
    2,
    ["lunch", "burguer"],
    ["dinner", "pasta"],
  ],
];

The array can have any number of items, each one is an array itself with the first item always being a number and the rest being arrays of 2 strings.

This is the type I came up with:

type Row = [number, ...[string, string]];

But it's not working, it says that the 2nd item should be a string instead of an array of strings:

Type '[string, string]' is not assignable to type 'string'.

Here's a playground with an example .

Answer 1

A rest element in a tuple type should be of the form [...YourDesiredElementType[]] . You want elements to be [string, string] , so the rest element looks like ...[string, string][] :

type Row = [number, ...[string, string][]];

And then things work as desired:

const rows: Row[] = [
  [
    1,
    ["bananas", "apples"],
    ["steak", "burguer"],
  ],
  [
    2,
    ["orange", "lemon"],
    ["pizza", "pasta"],
  ],
]; // okay

Playground link to code