sindresorhus/type-fest

`EmptyArray` type

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#929 opened on Aug 6, 2024

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 (2 comments) (0 reactions) (0 assignees)TypeScript (12,328 stars) (471 forks)batch import
help wantedtype addition

Description

There is EmptyObject, and I think a EmptyArray type for a strictly empty array would be useful.

One use case of empty array with React to avoid re-renders because of unstable default prop:

const defaultArr = [];
const Component = ({arr = defaultArr}) => arr.join(",");

Contributor guide

Tech stack
typescript
Domain
frontenddeveloper experience
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic TypeScriptFamiliarity with type fest library structure
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75
Research direction
The EmptyArray type should be defined in a new file source/empty array.d.ts, following the same pattern as source/empty object.d.ts. It should use a generic parameter T and extend an empty tuple type. The type should be exported in the main index.d.ts. Ensure tests are added under test d/ to verify that EmptyArray only allows an empty array and rejects non empty arrays. The existing EmptyObject type can serve as a reference for implementation and testing.