FastHtmlDiff

This gem performs a diff on two input HTML files (outputting the result in HTML as well). It's built for speed, using tried-and-true UNIX diff as the LCS algorithm. The implementation works directly on the DOM to ensure the output always remains valid.

Add this line to your application's Gemfile:

gem 'fast_html_diff'

And then execute:

$ bundle

Or install it yourself as:

$ gem install fast_html_diff

Basic usage:

result_html_str = FastHtmlDiff::DiffBuilder.new(string_a,string_b).build

With options (see below for details):

result_html_str = FastHtmlDiff::DiffBuilder.new(string_a,string_b,
                                                simplify_html: true, try_hard: true).build

• ignore_punctuation: boolean [default: true]
• case_insensitive: boolean [default: true]
• tokenizer_regexp: regexp [default: %r{([^A-Za-z0-9]+)};] Make sure to include the outer parentheses. This option overrides any "ignore_punctuation" setting.
• diff_cmd: str [default: 'diff']. May be useful if you only have diff available through cygwin or a Windows port.
• try_hard: boolean [default: false]. Try hard to find smaller-length matches (at a bit of a performance cost).
• simplify_html: boolean [default: false]. Strips HTML to only the permitted tags, giving better output format where the structure of the two inputs differ greatly.
• simplified_html_tags: array of strings [default %w(html body p strong em ul ol li)]

Insertions are wrapped in <ins>; Deletions are wrapped <del>. Add the following CSS for much nicer looking output:

ins {
    text-decoration: none;
    background-color: #a3ffad;
}
del {
    color: #ff5d5a;
    background-color: #b4ecff;
}

(c) 2013, Kent Mewhort, licensed under BSD. See LICENSE.txt for details.