Get Xaringan incremental animations to print to PDF?

When you're on an incremental slide then the class has-continuation is added to it and the corresponding print is set to display:none. To print out the incremental slides you need to overwrite this behaviour by inserting below to your css file:

@media print {
  .has-continuation {
    display: block !important;
  }
}

Small addition to @Emi's answer: if you use the package xaringanthemer, you can add the code in extra_css:

```{r xaringan-themer, include=FALSE, warning=FALSE}
library(xaringanthemer)
style_mono_accent(
  base_color = "#1c5253",
  extra_css = list(
    ".has-continuation" = list(
      "display" = "block !important"
    )
  )
)
```