fix(css): clarify angle return wording for atan, asin, acos #42426

kashish2710 · 2025-12-16T10:07:03Z

Clarifies the return value wording for CSS trigonometric functions atan(), asin(), and acos()
by removing references to "number of radians" and consistently describing the result
as an <angle>, aligning with existing guidance.

Corrects an incorrect calculation in the documentation warning.

github-actions · 2025-12-16T10:07:42Z

files/en-us/web/css/reference/values/asin/index.md

 ---

-The **`asin()`** [CSS](/en-US/docs/Web/CSS) [function](/en-US/docs/Web/CSS/Reference/Values/Functions) is a trigonometric function that returns the inverse sine of a number between `-1` and `1`. The function contains a single calculation that returns the number of radians representing an {{cssxref("&lt;angle&gt;")}} between `-90deg` and `90deg`.
+The **`asin()`** [CSS](/en-US/docs/Web/CSS) [function](/en-US/docs/Web/CSS/Reference/Values/Functions) is a trigonometric function that returns the inverse sine of a number between `-1` and `1`. The function contains a single calculation that returns an {{cssxref("<angle>")}} between `-90deg` and `90deg`.


[markdownlint] _{reported by reviewdog 🐶}
error MD033/no-inline-html Inline HTML [Element: angle]

github-actions · 2025-12-16T10:07:42Z

files/en-us/web/css/reference/values/atan/index.md

 ---

-The **`atan()`** [CSS](/en-US/docs/Web/CSS) [function](/en-US/docs/Web/CSS/Reference/Values/Functions) is a trigonometric function that returns the inverse tangent of a number between `-∞` and `+∞`. The function contains a single calculation that returns the number of radians representing an {{cssxref("&lt;angle&gt;")}} between `-90deg` and `90deg`.
+The **`atan()`** [CSS](/en-US/docs/Web/CSS) [function](/en-US/docs/Web/CSS/Reference/Values/Functions) is a trigonometric function that returns the inverse tangent of a number between `-∞` and `+∞`. The function contains a single calculation that returns an {{cssxref("<angle>")}} between `-90deg` and `90deg`.


[markdownlint] _{reported by reviewdog 🐶}
error MD033/no-inline-html Inline HTML [Element: angle]

github-actions · 2025-12-16T10:08:30Z

Preview URLs

Flaws (69)

Note! 1 document with no flaws that don't need to be listed. 🎉

URL: /en-US/docs/Web/CSS/Reference/Values/acos
Title: acos()
Flaw count: 23

broken_links:
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#single_bar is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- and 18 more flaws omitted

URL: /en-US/docs/Web/CSS/Reference/Values/asin
Title: asin()
Flaw count: 23

broken_links:
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#single_bar is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- and 18 more flaws omitted

URL: /en-US/docs/Web/CSS/Reference/Values/atan
Title: atan()
Flaw count: 23

broken_links:
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#single_bar is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- Link /en-US/docs/Web/CSS/CSS_values_and_units/Value_definition_syntax#brackets is a redirect
- and 18 more flaws omitted

(comment last updated: 2025-12-16 14:39:46)

kashish2710 · 2025-12-16T10:18:55Z

Hi! This PR clarifies the return value wording for atan(), asin(), and acos()
by consistently describing the result as an , as discussed in #42283.
Please let me know if any changes are needed. Thanks!

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

chrisdavidmills

Hi @kashish2710, and thank you for your work on this. The updated wording makes more sense. I just had one comment on an unrelated change that seems to have slipped in.

chrisdavidmills · 2025-12-16T11:57:06Z

files/en-us/web/api/window/requestanimationframe/index.md

 > The spec doesn't specify the overflowing behavior, so browsers have divergent behaviors. When overflowing, the value would either wrap around to 0, to a negative value, or fail with an error.
 > Unless overflow throws, request IDs are also not truly unique because there are only finitely many 32-bit integers for possibly infinitely many callbacks.
-> Note, however, that it would take ~500 days to reach the issue when rendering at 60Hz with 100 calls to `requestAnimationFrame()` per frame.
+> Note, however, that it would take approximately 800 days to reach the issue when rendering at 60Hz with a single call to requestAnimationFrame() per frame.


This isn't related to the rest of the PR. Did it get added by mistake? If it is still valid, can you remove it from here and then submit it as a separate PR? Thanks.

github-actions · 2025-12-16T14:22:30Z

This pull request has merge conflicts that must be resolved before it can be merged.

github-actions · 2025-12-16T14:22:55Z

files/en-us/web/api/window/requestanimationframe/index.md

-> Note, however, that it would take ~500 days to reach the issue when rendering at 60Hz with 100 calls to `requestAnimationFrame()` per frame.
+> Note, however, that it would take ~500 days to reach the issue when rendering at 60Hz with 100 calls to requestAnimationFrame() per frame.
+



[mdn-linter] _{reported by reviewdog 🐶}

Suggested change

kashish2710 · 2025-12-16T14:31:34Z

Thanks for the review! The unrelated requestAnimationFrame change has now been reverted from this PR, and the conflict is resolved. Appreciate your guidance.

chrisdavidmills

LGTM; thanks again, @kashish2710.

kashish2710 added 6 commits December 15, 2025 19:04

Fix incorrect requestAnimationFrame overflow calculation

5089265

Corrects an incorrect calculation in the documentation warning.

Update index.md

a94f72f

Update index.md

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fix(css): clarify return value wording for acos()

a5b128e

fix(css): clarify return value wording for asin()

f230f57

fix(css): clarify return value wording for atan()

f642c53

kashish2710 requested review from a team as code owners December 16, 2025 10:07

kashish2710 requested review from chrisdavidmills and hamishwillee and removed request for a team December 16, 2025 10:07

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kashish2710 added 3 commits December 16, 2025 15:40

Update index.md

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Update index.md

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Update index.md

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chrisdavidmills and others added 4 commits December 16, 2025 11:46

Update files/en-us/web/css/reference/values/asin/index.md

6425b0c

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Update files/en-us/web/css/reference/values/atan/index.md

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Update files/en-us/web/css/reference/values/asin/index.md

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Update files/en-us/web/css/reference/values/atan/index.md

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chrisdavidmills requested changes Dec 16, 2025

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chore: revert unrelated requestAnimationFrame change

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Update index.md

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Merge branch 'main' into fix-angle-return

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chrisdavidmills merged commit c087bbb into mdn:main Dec 16, 2025
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chrisdavidmills mentioned this pull request Dec 17, 2025

atan2() calculation always returns an <angle> in degrees, not radians #42283

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		> Note, however, that it would take ~500 days to reach the issue when rendering at 60Hz with 100 calls to `requestAnimationFrame()` per frame.
		> Note, however, that it would take ~500 days to reach the issue when rendering at 60Hz with 100 calls to requestAnimationFrame() per frame.

fix(css): clarify angle return wording for atan, asin, acos #42426

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