ifelse action depending on document type in rmarkdown

Question

When preparing reports using rmarkdown: http://rmarkdown.rstudio.com/ one may want the document to render differently depending upon the document type. For ins

Answer 1

As pointed out in an answer to a related question, knitr 1.18 introduced the following functions

knitr::is_html_output()
knitr::is_latex_output()

As the name suggests, is_html_output() checks if the output is HTML. You would add something like this to foo.Rmd:

```{r results='asis'}
if (knitr::is_html_output()) {
    cat('')
} else {
    cat("https://www.youtube.com/watch?v=ekBJgsfKnlw")
}
```