ERB::Formatter

You can install the gem using Bundler or by installing it directly via RubyGems.

To add it to your application's Gemfile:

$ bundle add erb-formatter

Or install it globally on your system:

$ gem install erb-formatter

To automatically format ERB files during git commits using lint-staged, add the following configuration to your package.json:

"lint-staged": {
  "*.html.erb": "bundle exec erb-format --write"
}

You can use the ERB::Formatter.format method to format ERB strings programmatically within your Ruby applications.

require 'erb/formatter'

formatted = ERB::Formatter.format <<-ERB
<div        >
            asdf
                  <% if 123%>
                      <%='foobar'%> <%end-%>
           </div>
ERB

# => "<div>\n  asdf\n  <% if 123 %>\n    <%= 'foobar' %>\n  <% end -%>
</div>\n"

If the ERB or HTML structure is invalid (e.g., unmatched tags or bad attribute syntax), ERB::Formatter raises an ERB::Formatter::Error.

Error messages include:

• The filename and line number.
• The specific error message (e.g., Unmatched close tag, Bad attribute, or Unknown tag).
• A visual representation of the formatted output up to the error point.
• A stack trace showing the tag stack at the time of the error.

The erb-format CLI tool allows you to format files in-place or via stdin/stdout.

Update files in-place: Use the --write flag to modify files directly.

Use stdin/stdout: Useful for editor integrations. Pipe content into the command using --stdin.

Run erb-format --help to see all available options.

# Update files in-place
$ erb-format app/views/**/*.html.erb --write

# Use stdin/stdout
$ echo "<div       > asdf  <% if 123%> <%='foobar'%> <%end-%>  </div>" | erb-format --stdin

To use advanced configuration, instantiate ERB::Formatter.new with the following options:

• source (String): The ERB content to format.
• line_width (Integer): The maximum line length (default: 80).
• single_class_per_line (Boolean): If true, each CSS class in a class attribute will be placed on its own line. (default: false).
• filename (String): The name of the file being formatted, used in error messages (default: '(erb)').
• css_class_sorter (Proc): A proc used to sort CSS classes within the class attribute.
• debug (Boolean): Enables debug output (uses $DEBUG).

formatter = ERB::Formatter.new(
  source,
  line_width: 100,
  single_class_per_line: true,
  filename: 'views/index.html.erb',
  css_class_sorter: ->(classes) { classes.sort }
)

puts formatter.html

The primary way to use this library is via the ERB::Formatter.format class method. It takes a source string and returns a formatted version of the ERB content. You can optionally provide a filename for better error reporting.

By default, it uses a line width of 80 characters. You can customize the formatting behavior by instantiating ERB::Formatter.new directly if you need more granular control over options like line_width, single_class_per_line, or css_class_sorter.

require 'erb/formatter'

source = "<div>\n  <% if true %>\n    <%= 'hello' %>\n  <% end %>\n</div>"
formatted = ERB::Formatter.format(source)
puts formatted

The following flags are available for the erb-formatter command-line tool:

FILENAME...           The files to be formatted

-w, --[no-]write      Write file
--stdin-filename FILEPATH  Set the stdin filename (implies --stdin)
--[no-]stdin           Read the file from stdin
--print-width WIDTH   Set the formatted output width
--single-class-per-line  Print each class on a separate line
--tailwind-output-path PATH  Set the path to the tailwind output file
--[no-]debug           Enable debug mode
--fail-level LEVEL     'check' exits(1) on any formatting changes
-h, --help             Prints this help
-v, --version          Show ERB::Formatter version number and quit

The erb-format executable is a command-line interface for formatting ERB files. It is invoked via the terminal and processes arguments passed through ARGV. To use it, ensure the erb-formatter gem is installed and the executable is in your PATH.

# Example usage (exact flags depend on the underlying CommandLine implementation)
```bash
erb-format path/to/file.erb

You can integrate Tailwind CSS class sorting by providing the path to your generated Tailwind CSS output file using the --tailwind-output-path flag. This allows the formatter to use the actual CSS selectors from your project to sort classes within your ERB templates.

erb-formatter my_template.erb --tailwind-output-path ./dist/output.css

You can pipe ERB content into the formatter using the --stdin flag. If you provide a filename via --stdin-filename, it will be used as the filename for the formatting process.

# Basic stdin usage
cat template.erb | erb-formatter --stdin

# Stdin with a specific filename
echo "<% if true %>hello<% end %>" | erb-formatter --stdin --stdin-filename test.erb