Microsoft/TypeScript

Suggestion: use numeric literals for `BYTES_PER_ELEMENT`

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#59,557 opened on Aug 8, 2024

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Domain: lib.d.tsExperience EnhancementHelp WantedSuggestion

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Description

⚙ Compilation target

ES5+

⚙ Library

lib.es5.d.ts, lib.es2022.bigint.d.ts

Missing / Incorrect Definition

Suggesting to change the BYTES_PER_ELEMENT static and instance properties as follows:

interface Uint8Array {
    // ...
-   readonly BYTES_PER_ELEMENT: number;
+   readonly BYTES_PER_ELEMENT: 1;
    // ...
}

interface BigInt64ArrayConstructor {
    // ...
-   readonly BYTES_PER_ELEMENT: number;
+   readonly BYTES_PER_ELEMENT: 8;
    // ...
}

Etc.

Sample Code

declare function fn(bytesPerElement: 1 | 2 | 4 | 8): void
// currently reports "Argument of type 'number' is not assignable to parameter of type '1 | 2 | 4 | 8'".
fn(Uint32Array.BYTES_PER_ELEMENT)

Documentation Link

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/BYTES_PER_ELEMENT#examples

Contributor guide

Research direction
Locate the typed array interface definitions in lib.es5.d.ts and lib.es2022.bigint.d.ts. Replace `readonly BYTES PER ELEMENT: number;` with the corresponding numeric literal (1, 2, 4, or 8) for each typed array. Verify the change compiles correctly and passes tests.
Tech stack
typescript
Domain
compilers
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
1
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitTypeScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
90