[FR] Ability to hide footer on specific slides including title-slide

[cderv]

Bug description

This relates to discussion in #825 and comment in #1391 (comment)

When a custom footer is set to

format: 
  revealjs:
    footer: Custom footer

It is possible to hide it on a specific slide using the trick of inserting an empty slide footer

# Slide 2

content 

::: footer
:::

However, this does not work on first slide at first

---
format: 
  revealjs:
    footer: Custom footer
---

# Slide 1 

content

::: footer
:::

# Slide 2

content 

This is because the feature (or free riding feature) rely on the per side footer overwrite using a slidechanged event which does not happen when presentation is loaded first time

quarto-cli/src/resources/formats/revealjs/plugins/support/support.js

Lines 117 to 133 in 763b0ed

	deck.on("slidechanged", function (ev) {
	const prevSlideFooter = document.querySelector(
	".reveal > .footer:not(.footer-default)"
	);
	if (prevSlideFooter) {
	prevSlideFooter.remove();
	}
	const currentSlideFooter = ev.currentSlide.querySelector(".footer");
	if (currentSlideFooter) {
	defaultFooterDiv.style.display = "none";
	const slideFooter = currentSlideFooter.cloneNode(true);
	handleLinkClickEvents(deck, slideFooter);
	deck.getRevealElement().appendChild(slideFooter);
	} else {
	defaultFooterDiv.style.display = "block";
	}
	});

This means that in the example above if you go to slide 2 then back to slide 1, it will hide the footer.

Hiding footer on title slide can be useful when you want to do a custom one like in #1391 (comment) example (https://github.com/giabaio/quarto-slides/blob/main/assets/title-slide.qmd)

Having a real mechanism to hide a footer (like adding .no-footer class on a slide maybe ?) would be a plus

[giabaio]

Thanks @cderv 👍

[mcanouil]

FYI:

• Related discussions:
  • Reveal.js Presentation: Title slide without page number and logo #557
  • revealjs presentation: hiding footer and slide menu control for a specific slide #825
  • Hide slide menu button when printing slides #4181
  • Way to remove slide-number for n^th slide in a revealjs presentation? #5566

[mcanouil]

FYI

• to hide the slide menu button on title slide:

include-after-body:
  - text: |
      <script type="text/javascript">
      Reveal.addEventListener('ready', (event) => {
        if (event.indexh === 0) {
          document.querySelector("div.slide-menu-button").style.display = "none";
        } else {
          document.querySelector("div.slide-menu-button").style.display = "block";
        }
      });
      Reveal.addEventListener('slidechanged', (event) => {
        if (event.indexh === 0) {
          document.querySelector("div.slide-menu-button").style.display = "none";
        } else {
          document.querySelector("div.slide-menu-button").style.display = "block";
        }
      });
      </script>

• to hide only the slide number on title slide

/*-- scss:rules --*/

.reveal .slide-number > a[href*='title-slide'] {
  display: none;
}