Multiline highlighting with Highlight.js

This presentation shows the use of the new highlighting features which were introduced with Reveal.js v3.9.0.

Prerequisite

Disable codeFences in to your config.toml to prevent Hugo’s built-in highlighting for code inside of --- fences.

[markup.highlight]
codeFences = false

Theme

Specify a theme for Highlight.js in config.toml

[params.reveal_hugo]
highlight_theme = "github"

…or in the _index.md front matter

[reveal_hugo]
highlight_theme = "github"

Usage

The line highlighting is configured by adding {} immediately after the language selection of the markdown code block.

```foo{}

```

Just line numbers

{}

```go{}
package main
import "fmt"
func main() {
    fmt.Println("Hello world!")
}
```

package main
import "fmt"
func main() {
    fmt.Println("Hello world!")
}

Highlight specific lines

{<line numbers separated by comma>}

```go{1,3-5}
package main
import "fmt"
func main() {
    fmt.Println("Hello world!")
}
```

package main
import "fmt"
func main() {
    fmt.Println("Hello world!")
}

Multi step highlight

{<line numbers separated by pipe>}

```go{1|2|3-5}
package main
import "fmt"
func main() {
    fmt.Println("Hello world!")
}
```

package main
import "fmt"
func main() {
    fmt.Println("Hello world!")
}

Hiding the line numbers

There is no Reveal.js parameter to use line highlighting without line numbers. However it can be achieved by adding the some custom CSS.

<style>
  .hljs-ln-numbers {
    display: none;
  }
</style>

💡 Put the custom CSS in either of these partials:

# for all presentations
layouts/partials/reveal-hugo/body.html

# for one presentation
layouts/partials/{presentation-name}/reveal-hugo/body.html

Thanks!