fix: type observer callback entries and box sizes as non-empty tuples#2515
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homayounmmdy wants to merge 1 commit into
Open
fix: type observer callback entries and box sizes as non-empty tuples#2515homayounmmdy wants to merge 1 commit into
homayounmmdy wants to merge 1 commit into
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- Updates ResizeObserverCallback, IntersectionObserverCallback, and MutationCallback to use [T, ...T[]] instead of T[]. - Updates ResizeObserverEntry contentBoxSize, borderBoxSize, and devicePixelContentBoxSize to be non-empty readonly tuples. - Rationale: Browser specs guarantee these callbacks are only invoked when there is at least one observation, making the empty array case impossible at runtime. - References: microsoft/TypeScript#61691
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Thanks for the PR! This section of the codebase is owned by @saschanaz - if they write a comment saying "LGTM" then it will be merged. |
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@microsoft-github-policy-service agree |
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This PR addresses microsoft/TypeScript#61691.
The Problem:
The current Web IDL spec types observer callback parameters (like
entriesinResizeObserverCallback) as standard arrays (T[]). However, the browser specification guarantees that these callbacks are only ever invoked when there is at least one observation. This forces developers to use unnecessary non-null assertions (!) or runtime checks for a state that is theoretically impossible.The Solution:
This PR adds manual overrides in
overridingTypes.jsoncto enforce a non-empty tuple type ([T, ...T[]]) for:ResizeObserverCallbackIntersectionObserverCallbackMutationCallbackResizeObserverEntry'scontentBoxSize,borderBoxSize, anddevicePixelContentBoxSizeproperties.Verification:
Ran
npm run generateand verified the output inbaselines/dom.generated.d.tsreflects the correct non-empty tuple types without breaking the build.