Incomplete Documentation: loop mode `centeredSlides` and `slidesPerView` behavior not described

[y-hsgw]

Clear and concise description of the problem

As a developer using Swiper, I want the documentation for loop mode to state the correct minimum number of slides required when centeredSlides is enabled and slidesPerView is even, since Swiper's internal logic increases this number compared to what is currently documented.

Suggested solution

Update the documentation for Swiper loop mode (https://swiperjs.com/swiper-api#param-loop) to cover:

• What happens when centeredSlides: true is used with loop mode.
• The internal logic (found in src/core/loop/loopFix.mjs):

swiper/src/core/loop/loopFix.mjs

Lines 44 to 46 in ec4977b

	if (bothDirections && slidesPerView % 2 === 0) {
	slidesPerView = slidesPerView + 1;
	}

• When using bothDirections (centeredSlides or slidesOffsetBefore/After), if slidesPerView is even, it will be incremented by 1 internally.
• Implications for minimal required slide count, loopedSlides, or layouts.

This will help users anticipate possible layout issues or differences between configuration and the actual displayed result.

Alternative

No response

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

Would you like to open a PR for this feature?

• I'm willing to open a PR

[y-hsgw]

I realized that I mistakenly created this issue as a feature request.
This should be a documentation fix instead.
Sorry for the confusion.

[nolimits4web]

Hi, what behavior are you talking about? It doesn't change slidesPerView, that part of code used only to calculate slides to loop, nothing visually changed

[y-hsgw]

@nolimits4web
Hi, thank you for your response.
Sorry for the confusion.😵‍💫

I am talking about the required minimum number of slides for loop mode to work, not about the visual slidesPerView value.

The documentation says:

Set to true to enable continuous loop mode
Because of nature of how the loop mode works (it will rearrange slides), total number of slides must be:

• more than or equal to slidesPerView + slidesPerGroup

However, there is no specific mention about the case when slidesPerView is even and centeredSlides is enabled, which I think can be confusing for some users.

For example, when using slidesPerView: 2 and centeredSlides: true:
According to the documentation:

slidesPerView + slidesPerGroup
2 + 1 = 3

But in actual behavior, the required number of slides becomes 5, as a result of the following logic:

swiper/src/core/loop/loopFix.mjs

Lines 44 to 46 in ec4977b

	if (bothDirections && slidesPerView % 2 === 0) {
	slidesPerView = slidesPerView + 1;
	}

swiper/src/core/loop/loopFix.mjs

Lines 50 to 52 in ec4977b

	let loopedSlides = bothDirections
	? Math.max(slidesPerGroup, Math.ceil(slidesPerView / 2))
	: slidesPerGroup;

If you provide only 3 slides as described in the documentation, you'll get a warning.

swiper/src/core/loop/loopFix.mjs

Lines 61 to 67 in ec4977b

	if (
	slides.length < slidesPerView + loopedSlides ||
	(swiper.params.effect === 'cards' && slides.length < slidesPerView + loopedSlides * 2)
	) {
	showWarning(
	'Swiper Loop Warning: The number of slides is not enough for loop mode, it will be disabled or not function properly. You need to add more slides (or make duplicates) or lower the values of slidesPerView and slidesPerGroup parameters',
	);

This difference between the documented rule and internal calculation is what I'm pointing out as potentially confusing.