ERB template syntax in Ruby on Rails - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the ERB tag <%= %> do in a Rails view?

It evaluates Ruby code inside the tag and inserts the result into the HTML output.

beginner

What is the difference between <% %> and <%# %> in ERB?

<% %> runs Ruby code without outputting it, while <%# %> is a comment and does not run or output anything.

beginner

How do you write a Ruby if statement in ERB to conditionally show content?

Use <% if condition %> to start, then HTML or ERB code, and close with <% end %>.

intermediate

What does <%== %> do in ERB templates?

It outputs raw HTML without escaping it, so be careful to avoid XSS security risks.

beginner

How can you embed Ruby variables inside HTML using ERB?

Use <%= variable_name %> to insert the variable's value into the HTML output.

Which ERB tag outputs the result of Ruby code into the HTML?

A <%= %>

B <% %>

C <%# %>

D <%== %>

The <%= %> tag evaluates Ruby code and inserts the result into the HTML output.

What does the ERB tag <%# %> do?

A Comments out code, no execution or output

B Runs Ruby code without output

C Runs Ruby code and outputs result

D Outputs raw HTML without escaping

The <%# %> tag is a comment in ERB and does not run or output anything.

How do you write a loop in ERB to repeat HTML content?

A <% if item in list %> ... <% end %>

B <%= for item in list %> ... <%= end %>

C <% for item in list %> ... <% end %>

D <%# for item in list %> ... <%# end %>

Use <% for item in list %> to start the loop and <% end %> to close it, running Ruby code without outputting the loop itself.

Which ERB tag should you use to insert unescaped HTML safely?

A <%= %>

B <%== %>

C <%# %>

D <% %>

The <%== %> tag outputs raw HTML without escaping, but use it carefully to avoid security risks.

What happens if you use <% %> in ERB?

A Raw HTML is output

B Ruby code runs and output is inserted

C Code is commented out

D Ruby code runs but no output is inserted

The <% %> tag runs Ruby code but does not insert any output into the HTML.

Explain how to use ERB tags to insert Ruby code and output into an HTML template.

Think about which tags run code, output, or comment.

Describe how to write a conditional statement in ERB to show content only when a condition is true.

Remember ERB uses Ruby control flow syntax inside tags.