microsoft / microsoft/TypeScript

lib.dom: DOMatrix constructor accepts TypedArrays, not only Arrays.

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Bug Domain: lib.d.ts Help Wanted
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Description

⚙ Compilation target

n/a

⚙ Library

lib.dom

Missing / Incorrect Definition

DOMMatrix and DOMMatrixReadonly constructors are typed as accepting only number[] but they also accept TypedArrays in all browsers.

The following code works in all browsers:

Sample Code
new DOMMatrix(new Float32Array(16))
Documentation Link

The MDN documentation doesn't really mention this detail, and the spec mentions a "sequence" which to me isn't very specific. Isn't a TypedArray a "sequence of numbers"?

Perhaps the type should probably be ArrayLike<number>.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating the lib.dom declarations for the DOMMatrix and DOMMatrixReadonly constructors and compare their current parameter types with the behavior shown by new DOMMatrix(new Float32Array(16)). Check the relevant declaration tests if available; done means both constructors accept typed arrays as well as regular number arrays.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
web-dev
Issue type
Bug
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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