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yasen
yasen

Reputation: 1260

Difference between <% and <%=

Can somebody tell me what is the difference between the <%= %> and <% %> tags in erb? In which case should I use which one? What other tags can I use and what is their meaning?

Upvotes: 1

Views: 132

Answers (3)

Nick Ginanto
Nick Ginanto

Reputation: 32130

As said

<% %>

will take the ruby code inside and evaluate it

<%= %>

will take the ruby code inside and evaluate it and print the result on the screen, which generally means will return a printable result which can be used in html as normal text

so doing 

<div class="<% 'myclass' %>">

will result in 

<div class="">

and <div class="<%= 'myclass' %>"> will result in 

<div class="myclass">

you can see this railscast which explains it further http://railscasts.com/episodes/100-5-view-tips

Also, you will probably encounter this in the future and even forget I wrote this but it might be useful anyhow

in some cases, not every line of ruby code should be a line of <% %>. for example - using a case switch

this won't work:

<% case my_var %>
<% when 10 %>
<% some ruby code %>
<% end %>

but this will

<% case my_var 
  when 10 %>
<% some ruby code %>
<% end %>

so be wary of that

Upvotes: 6

LHH
LHH

Reputation: 3323

<% %>

Executes the ruby code within the brackets.

<%= %>

Prints something into erb file.

Upvotes: 1

amit karsale
amit karsale

Reputation: 755

<%= %> is used when you want your executed ruby to be output to screen, that means anything written inside this block gets printed in your output screen,

where as <% %> block is used to perform your ruby logic part, for eg your if condition, loop statement, etc..

Upvotes: 1

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