Wants to truncate an HTML string properly? This Ruby gem is for you.
Ruby
Latest commit 45382ea Sep 4, 2015 @nono Merge pull request #20 from makaio/patch-1
Set uses #delete, not #remove

README.md

HTML Truncator

Wants to truncate an HTML string properly? This gem is for you. It's powered by Nokogiri!

How to use it

It's very simple. Install it with rubygems:

gem install html_truncator

Or, if you use bundler, add it to your Gemfile:

gem "html_truncator", "~>0.2"

Then you can use it in your code:

require "html_truncator"
HTML_Truncator.truncate("<p>Lorem ipsum dolor sit amet.</p>", 3)
# => "<p>Lorem ipsum dolor…</p>"

The HTML_Truncator class has only one method, truncate, with 3 arguments:

  • the HTML-formatted string to truncate
  • the number of words to keep (real words, tags and attributes aren't count)
  • some options like the ellipsis (optional, '…' by default).

And 3 attributes:

  • ellipsable_tags, which lists the tags that can contain the ellipsis (by default: p ol ul li div header article nav section footer aside dd dt dl)
  • self_closing_tags, with the tags to keep when empty (by default: br hr img param embed)
  • punctuation_chars, with the punctation characters to remove before the ellipsis (by default: , . : ; ! ?).

Examples

A simple example:

HTML_Truncator.truncate("<p>Lorem ipsum dolor sit amet.</p>", 3)
# => "<p>Lorem ipsum dolor…</p>"

If the text is too short to be truncated, it won't be modified:

HTML_Truncator.truncate("<p>Lorem ipsum dolor sit amet.</p>", 5)
# => "<p>Lorem ipsum dolor sit amet.</p>"

If you prefer, you can have the length in characters instead of words:

HTML_Truncator.truncate("<p>Lorem ipsum dolor sit amet.</p>", 12, :length_in_chars => true)
# => "<p>Lorem ipsum…</p>"

It doesn't cut inside a word but goes back to the immediately preceding word boundary:

HTML_Truncator.truncate("<p>Lorem ipsum dolor sit amet.</p>", 10, :length_in_chars => true)
# => "<p>Lorem…</p>"

You can customize the ellipsis:

HTML_Truncator.truncate("<p>Lorem ipsum dolor sit amet.</p>", 3, :ellipsis => " (truncated)")
# => "<p>Lorem ipsum dolor (truncated)</p>"

And even have HTML in the ellipsis:

HTML_Truncator.truncate("<p>Lorem ipsum dolor sit amet.</p>", 3, :ellipsis => '<a href="/more-to-read">...</a>')
# => "<p>Lorem ipsum dolor<a href="/more-to-read">...</a></p>"

The ellipsis is put at the right place, inside <p>, but not <i>:

HTML_Truncator.truncate("<p><i>Lorem ipsum dolor sit amet.</i></p>", 3)
# => "<p><i>Lorem ipsum dolor</i>…</p>"

And the punctation just before the ellipsis is not kept:

HTML_Truncator.truncate("<p>Lorem ipsum: lorem ipsum dolor sit amet.</p>", 2)
# => "<p>Lorem ipsum…</p>"

You can indicate that a tag can contain the ellipsis but adding it to the ellipsable_tags:

HTML_Truncator.ellipsable_tags << "blockquote"
HTML_Truncator.truncate("<blockquote>Lorem ipsum dolor sit amet.</blockquote>", 3)
# => "<blockquote>Lorem ipsum dolor…</blockquote>"

You can know if a string was truncated with the html_truncated? method:

HTML_Truncator.truncate("<p>Lorem ipsum dolor sit amet.</p>", 3).html_truncated?
# => true

You can ignore images in the text by overriding the self_closing_tags attribute:

HTML_Truncator.self_closing_tags.delete "img"
HTML_Truncator.truncate("<p>Lorem ipsum <img src='...'>dolor sit amet.</p>", 3)
# => "<p>Lorem ipsum dolor…</p>"

If you already have parsed an HTML document with Nokogiri, you can use it directly to truncate:

document = Nokogiri::HTML::DocumentFragment.parse(text)
# Doing something with this document
options = HTML_Truncator::DEFAULT_OPTIONS.merge(length_in_char: true)
document.truncate(12, options)

Alternatives

Rails has a truncate helper, but as the doc says:

Care should be taken if text contains HTML tags or entities, because truncation may produce invalid HTML (such as unbalanced or incomplete tags).

I know there are some Ruby code to truncate HTML, like:

But I'm not pleased with these solutions: they are either based on regexp for parsing the content (too fragile), they don't put the ellipsis where expected, they cut words and sometimes leave empty DOM nodes. So I made my own gem ;-)

Issues or Suggestions

Found an issue or have a suggestion? Please report it on Github's issue tracker.

If you wants to make a pull request, please check the specs before:

rspec spec

Credits

Thanks to François de Metz for his awesome help! Thanks to kuroir and benhutton for their suggestions.

The code is released under the MIT license. See the MIT-LICENSE file for the full license.

♡2011 by Bruno Michel. Copying is an act of love. Please copy and share.