Microsoft/TypeScript

lib.es*.d.ts: constructor methods

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#44,883 opened on Jul 3, 2021

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BugDomain: lib.d.tsHelp Wanted

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Description

lib Update Request

Configuration Check

My compilation target is ES2015 and my lib is the default.

Missing / Incorrect Definition

Array and other interfaces for built-ins do not declare their own constructor methods

Sample Code

[].constructor[Symbol.species];

Element implicitly has an 'any' type because expression of type 'unique symbol' can't be used to index type 'Function'.
  Property '[SymbolConstructor.species]' does not exist on type 'Function'.

The code compiles fine when defining the appropriate constructor method:

declare global {
  interface Array<T> {
    constructor: ArrayConstructor;
  }
}

Playground link

Documentation Link

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/constructor

Contributor guide

Research direction
Examine the lib.es*.d.ts files (e.g., lib.es5.d.ts) to find the interface for Array. Add a constructor property with type ArrayConstructor. Follow existing patterns in the file.
Tech stack
typescript
Domain
compilers
Issue type
Bug
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
TypeScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75