Linter Rule: Prefer direct ERB output over string interpolation

Rule: erb-prefer-direct-output

Description

Flags ERB output tags that contain a string literal, including interpolated strings. The text should be written directly in the template, and dynamic values should use separate ERB output tags.

Rationale

Wrapping static text in a string literal inside an ERB output tag is unnecessary. The text can be written directly in the template. For interpolated strings, each dynamic value should use its own ERB output tag, which is more idiomatic, easier to read, and avoids unnecessary string allocation.

Examples

✅ Good

Title

<%= key %>

<%= key %> (<%= participants.size %>)

Hello <%= name %>

🚫 Bad

<%= "Title" %>
Avoid outputting string literal `"Title"`. Write the text directly without wrapping it in an ERB output tag. (erb-prefer-direct-output)

<%= "#{key}" %>
Avoid outputting interpolated string `"#{key}"`. Use separate `<%= %>` tags for each dynamic value instead. (erb-prefer-direct-output)

<%= "#{key} (#{participants.size})" %>
Avoid outputting interpolated string `"#{key} (#{participants.size})"`. Use separate `<%= %>` tags for each dynamic value instead. (erb-prefer-direct-output)

<%= "Hello #{name}" %>
Avoid outputting interpolated string `"Hello #{name}"`. Use separate `<%= %>` tags for each dynamic value instead. (erb-prefer-direct-output)