Easy conditional style class names in Rails

How many times do you see something like this?

<%= 
  link_to("Somewhere", "#",
    class: "class-1 class-2#{" class-3" if true}"
  )
%>

# <a href="#" class="class-1 class-2 class-3">Somewhere</a>

Gross right!?

Take advantage of a token list instead.

It's also got a great alias in class_names

<%= 
  link_to("Somewhere", "#", 
    class: class_names("class-1 class-2", {"class-3": true})
  )
%>

# <a href="#" class="class-1 class-2 class-3">Somewhere</a>

As you see it can be passed different types and still generates down to a string list.

It works great with the current_page helper.

<%= 
  link_to("Home", root_path, 
    class: class_names({"active": current_page?(root_path)})
  )
%>

# <a href="/" class="active">Home</a>