Ruby on Rails - What does this symbol mean: <%- … -%> in erb?

Question

Just generated devise views and found in the generated erb.html :

<%- if controller_name != 'sessions' %>
  <%= link_to "Sign in", new_session_path(resource_name) %><br />
<% end -%>

What does <%- %> .. <% -%> , I know it is a monkey's question, but I don't know which keyword to search..so I came to the help of the invincible Stackoverflow..

Answer 1

吃掉空格，使呈现的HTML看起来更好。

Answer 2

You can place Ruby code within <% %>

<% Ruby code -- inline with output %>
<%= Ruby expression -- replace with result %>
<%# comment -- ignored -- useful in testing %>
% a line of Ruby code -- treated as <% line %> (optional -- see ERB.new)
%% replaced with % if first thing on a line and % processing is used
<%% or %%> -- replace with <% or %> respectively

Reference: http://ruby-doc.org/stdlib-1.9.3/libdoc/erb/rdoc/ERB.html