truncato

truncato is a Ruby library for truncating HTML strings keeping the markup valid.

In your Gemfile

gem 'truncato'

Truncato.truncate "<p>some text</p>", max_length: 4 #=> "<p>s...</p>"
Truncato.truncate "<p>some text</p>", max_length: 4, count_tags: false #=> "<p>some...</p>"

The configuration options are:

• max_length: The size, in characters, to truncate (30 by default)
• filtered_attributes: Array of attribute names that will be removed in the truncated string. This allows you to make the truncated string shorter by excluding the content of attributes you can discard in some given context, e.g HTML style attribute.
• filtered_tags: Array of tags that will be removed in the truncated string. If a tag is excluded, all the nested tags under it will be excluded too.
• count_tags: Boolean value indicating whether tags size should be considered when truncating (true by default)
• tail_before_final_tag: Boolean value indicating whether to apply a tail before the final closing tag (false by default)
• comments: Boolean value indicating whether to include comments in parsed results (false by default)
• tail: The string to append when the truncation occurs ('...' by default)
• count_tail: Boolean value indicating whether to include the tail within the bounds of the provided max length (false by default)

Truncato was designed with performance in mind. Its main motivation was that existing libs couldn't truncate a multiple-MB document into a few-KB one in a reasonable time. It uses the Nokogiri SAX parser.

There is a benchmark included that generates a synthetic XML of 4MB and truncates it to 400 KB. You can run the benchmark using

rake truncato:benchmark

There is a also a comparison benchmark that tests the previous data with other alternatives

rake truncato:vendor_compare

The results comparing truncato with other libs:

rake spec