I see some type definition like this in Typescript: deep keyof of a nested object :
type Prev = [never, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
11, 12, 13, 14, 15, 16, 17, 18, 19, 20, ...0[]]
I can't understand what the last part ...0[]
means.
Is there a document for this? Thanks
You need two pieces of information to understand this type:
The last element of a tuple type can be a rest element of the form
...X
, whereX
is an array type. A rest element indicates that the tuple type is open-ended and may have zero or more additional elements of the array element type. For example,[number, ...string[]]
means tuples with anumber
element followed by any number ofstring
elements.
const x: 0 = 0;
const y: 0 = 1; // ERROR: Type '1' is not assignable to type '0'.
Thus, the trailing ...0[]
in tuple type means: any number of zeroes
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