wtflayout.md

# layout.erb
<html>
<head>
  <title>My Site</title>
</head>
<body>
  <%= yield %>
</body>
</html>

# index.erb
get "/tasks" do
  @tasks = ["learn Ruby", "learn JavaScript"]

  erb :index
end

# new.erb
get "/tasks/new" do
  ...
  erb :new
end

ANY TIME you render a template, ie index.erb, new.erb, etc.

FIRST: the layout.erb is rendered until the yield is hit (if there is a layout.erb)

SECOND: the template you specified is rendered, for example new.erb

THIRD: you return to the layout.erb and finish loading any HTML

The layout allows you to have things that are common to all pages
for example, before the yield you might have a sweet top bar and search field you want on all pages
you might want a dope footer after the yield that will be loaded to every page

jennceng/wtflayout.md