从在ioslides中启用的高亮模式开始

Question

In ioslides presentation with Rmarkdown, there is an option to enable highlight mode in each slide by pressing h . Is there some way to make the highlight mode enabled by default and disable it by pressing h .

Answer 1

There is no built-in option to enable highlight mode by default.
This comes from these lines of JavaScript: here and here .
Highlight mode is removed when the speaker changes the slide.

However, there is a hacky way to highlight each slide by default.
In your project, create a new file (named for instance highlight.html ).
In this file, copy the following content:

<script type="text/javascript">
  SlideDeck.prototype.prevSlide = function(opt_dontPush) {
    if (this.curSlide_ > 0) {
      var bodyClassList = document.body.classList;
      bodyClassList.add('highlight-code');

      // Toggle off speaker notes if they're showing when we move backwards on the
      // main slides. If we're the speaker notes popup, leave them up.
      if (this.controller && !this.controller.isPopup) {
        bodyClassList.remove('with-notes');
      } else if (!this.controller) {
        bodyClassList.remove('with-notes');
      }

      this.prevSlide_ = this.curSlide_--;

      this.updateSlides_(opt_dontPush);
    }
  };

  SlideDeck.prototype.nextSlide = function(opt_dontPush) {
    if (!document.body.classList.contains('overview') && this.buildNextItem_()) {
      return;
    }

    if (this.curSlide_ < this.slides.length - 1) {
      var bodyClassList = document.body.classList;
      bodyClassList.add('highlight-code');

      // Toggle off speaker notes if they're showing when we advanced on the main
      // slides. If we're the speaker notes popup, leave them up.
      if (this.controller && !this.controller.isPopup) {
        bodyClassList.remove('with-notes');
      } else if (!this.controller) {
        bodyClassList.remove('with-notes');
      }

      this.prevSlide_ = this.curSlide_++;

      this.updateSlides_(opt_dontPush);
    }
  };
</script>

Now, modify the YAML header of the ioslides presentation:

---
title: "Highlighted"
author: "Romain Lesur"
date: "26/06/2018"
output: 
  ioslides_presentation:
    includes:
      after_body: highlight.html
---

It should do the trick.