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To make tabs for Info, Comments and Videos
< Feedback on Tabview YouTube Totara
How did you make the related videos scroll infinitely instead of having to press show more?
There is an yt custom element "ytd-continuation-item-renderer" in the end of the list.
It uses IntersectionObserver or similar to detect whether it appears, so indicating that the list is scrolled to the end.
Its controller has a "showButton" property. If it is true, the "Show More" button will appear and it will not auto load more.
Set it to false before the IntersectionObserver callback was triggered.

You can find the code in this script around 4066 ~ 4082

Thank you, I asked because I got permission to fix and repost an extension for tabbed YT and the related list shows the "Show more" only once when the extension is enabled. Problem is, even with your answer as to how you did it, my JS knowledge is practically non-existent so implementing something even remotely similar to yours might be less likely than humanity colonizing Mars. I might try asking the original author about how to do this but I've got little hope since they stopped updating their own repo of the extension years back.
I don't know which extension you are talking about.
I don't think other scripts will touch to these low level coding.
I think he/she just changed every thing entirely so the UI is broken.
You should avoid using such extension because YouTube is changing so fast. One day the extension might be not able to use.
It's this, forked from the original author: https://github.com/ChromiaCat/watch-and-read-comments-for-youtube
I like it more because in info/description tab it moves everything to the side, not just the description.
I have asked the original author as to what & why would cause that but maybe, in your spare time, you could take a look at it.
Indeed, for a while it was broken where it would fail to properly move stuff to the side, but I figured out it just needed a bit of updating on what it was targeting to resize & move. A few class names to update/add & it was working again, the js code didn't need any change at all.
How did you make the related videos scroll infinitely instead of having to press show more?