This interface describes my answers array (IActivityAnswer[]).
export interface IActivityAnswer {
createdAt: string;
id: string;
questionId: string;
score: number;
summary: string;
title: string;
commentCount?: number;
}
Some users won't have any answers (so they will have an empty array). How do I define a type for empty array. I want to accomplish this without using type any.
As of TypeScript 3.0, you can use the empty tuple type, written [].
const empty: [] = [];
However, even without this feature, I don't understand why you would need to use any since you could write something like
const empty = <never[] & {length: 0}>[];
The empty tuple type [] should be preferred as it provides more robust checking and better error messages when misused.
Type 'undefined[]' is not assignable to type 'never[]'.
[]. A type assertion is required. I've updated the answer accordingly.
const answerArray : Array<IActivityAnswer> = [ ];You can specify IActivityAnswer[] and the type would be defined as the following:
An array containing IActivityAnswer objects, or an array not containing IActivityAnswer objects, i.e. an empty array.
