Scroll By

[davidjerleke]

👉 Specification (implemented)

// adds to current scroll progress
// accepts a number from 0 - 1 representing % to add to the current scroll progress
// scroll to target is smooth

embla.scrollBy(0.5)

As discussed here and here in issue #21.

Special thanks

@xiel for this feature request.

Please react with --> 👍 if you want this to be implemented.

[davidjerleke]

Hello Felix (@xiel),

I'm looking into implementing this and I'd like to discuss the feature request further with you. By passing a fraction representing % to the embla.scrollBy(0.5) function, do you mean that the percentage to scroll should be calculated from the total scrollable distance or based on the current position?

Thank you in advance.

Kindly,
David

[xiel]

Hi David (@davidjerleke),

cool, looking forward to this feature!

I would expect scrollBy to work additive with scrollProgress. So when scrollProgress() is returning 0.5 and I would scrollBy(0.25), scrollProgress() would now return 0.75.

Cheers, Felix

[davidjerleke]

Hi again Felix (@xiel),

Thanks for getting back to me and I appreciate your clear explanation. We're on the same page then, so I'll let you know when I have something.

Best,
David

[davidjerleke]

Hello Felix (@xiel),

I'm happy to announce that I've released the scrollBy() feature with version 2.7.0 🚀. I've not had time to add it to the README though, but I'll add it as soon as possible.

How it works:

• ScrollBy adds to scrollProgress as we discussed.
• ScrollBy respects the scroll bounds when loop: false.

Let me know if it works as intended.

Cheers,
David

[xiel]

Thanks! Will check out soon

[davidjerleke]

@xiel I’ve added the CodeSandbox to the Readme now. Make sure that you download the latest patch version before trying it out. Enjoy!

[xiel]

Really cool! Was super easy to build a gallery with preview with this, so the previews scroll at the same time as the big images. I think I even like the softer movement as you still apply the spring when setting with scrollBy right?

https://codesandbox.io/s/embla-carousel-scrollby-we9j1

Maybe in the future the scrollBy method could take a second options object, in for

unit: 'percentage' | 'px' // percentage default
and hard: false | true //  false default

Because when I would like to control the gallery connected to a user gesture, it would be nicer to have the set hard I think.

[davidjerleke]

Hi Felix (@xiel),

I'm glad you like it. That's correct, scrollBy() will scroll smoothly to target as opposed to an instant setter. Thank you for your demonstration and ideas! I think you've mentioned these feature requests some time ago and I think they could be interesting additions to the API.

The unit part you mention should be a piece of cake because I already map px to percentage in the code. Regarding the hard part, I'm going to do some guessing but I think you're describing the feature request in issue #26, where I've asked you a question about the implementation. Please have a look at it when you have a moment to spare 🙂.

I'm going to close this issue and treat it as resolved. Feel free to open an issue about the unit part.

Best,
David