来源: https://stackoverflow.com/questions/52489261/typescript-can-i-define-an-n-length-tuple-type
Typescript 3 introduces rest elements in tuple types
The last element of a tuple type can be a rest element of the form ...X, where X is an array type
To restrict the length of a tuple we can use intersection with { length: N }
定义类型
type Tuple<TItem, TLength extends number> = [TItem, ...TItem[]] & { length: TLength };那么定长为6的数组就是
let matrix: Tuple<number, 6>
matrix = [1,2,3,4,5,6]