I wrote a Ruby method (for use as a Rails helper) to wordwrap text. It does not wrap within <pre></pre>, as those elements are styled with

max-width:100%;
overflow-x:auto;

to get scrollbars if their content is overlong. Also, it does not wrap inside HTML tags, since long src or href attributes shouldn't be broken up.

Perhaps there is a better solution, but I kind of like this:

class String
  # Replace the second of three capture groups with the given block.
  def midsub(regexp, &block)
    self.gsub(regexp) { $1 + yield($2) + $3 }
  end
end

def wordwrap(text, width=80, string="<wbr />")
  text.midsub(%r{(\A|</pre>)(.*?)(\Z|<pre(?: .+?)?>)}im) do |outside_pre|  # Not inside <pre></pre>
    outside_pre.midsub(%r{(\A|>)(.*?)(\Z|<)}m) do |outside_tags|  # Not inside < >, either
      outside_tags.gsub(/(\S{#{width}})(?=\S)/) { "#$1#{string}" }
    end
  end
end

test = "Lorem ipsum dolor sit amet, <pre>consectetur</pre> adipisicing elit, sed do eiusmod tempor <pre class='longlatinwordicus'>incididunt</pre> ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo <a href='longlatinwordicus'>consequat</a>. Duis aute irure dolor in <pre class='longlatinwordicus'><code>reprehenderit</code></pre> in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."

puts wordwrap(test, 5)

which outputs

Lorem ipsum dolor sit amet, <pre>consectetur</pre> adipi<wbr />sicin<wbr />g elit, sed do eiusm<wbr />od tempo<wbr />r <pre class='longlatinwordicus'>incididunt</pre> ut labor<wbr />e et dolor<wbr />e magna aliqu<wbr />a. Ut enim ad minim venia<wbr />m, quis nostr<wbr />ud exerc<wbr />itati<wbr />on ullam<wbr />co labor<wbr />is nisi ut aliqu<wbr />ip ex ea commo<wbr />do <a href='longlatinwordicus'>conse<wbr />quat</a>. Duis aute irure dolor in <pre class='longlatinwordicus'><code>reprehenderit</code></pre> in volup<wbr />tate velit esse cillu<wbr />m dolor<wbr />e eu fugia<wbr />t nulla paria<wbr />tur. Excep<wbr />teur sint occae<wbr />cat cupid<wbr />atat non proid<wbr />ent, sunt in culpa qui offic<wbr />ia deser<wbr />unt molli<wbr />t anim id est labor<wbr />um.