module ActionView::Helpers::TextHelper

# => "Once\r\nupon\r\na\r\ntime"
word_wrap('Once upon a time', line_width: 1, break_sequence: "\r\n")

You can also specify a custom +break_sequence+ ("\n" by default):

# => "Once\nupon\na\ntime"
word_wrap('Once upon a time', line_width: 1)

# => "Once\nupon a\ntime"
word_wrap('Once upon a time', line_width: 8)

# => "Once upon a time, in a kingdom called Far Far Away, a king fell ill, and finding\na successor to the throne turned out to be more trouble than anyone could have\nimagined..."
word_wrap('Once upon a time, in a kingdom called Far Far Away, a king fell ill, and finding a successor to the throne turned out to be more trouble than anyone could have imagined...')

# => "Once upon a time"
word_wrap('Once upon a time')

(which is 80 by default).
breaks on the first whitespace character that does not exceed +line_width+
Wraps the +text+ into lines no longer than +line_width+ width. This method

def word_wrap(text, line_width: 80, break_sequence: "\n")
  return +"" if text.empty?
  # Match up to `line_width` characters, followed by one of
  #   (1) non-newline whitespace plus an optional newline
  #   (2) the end of the string, ignoring any trailing newlines
  #   (3) a newline
  #
  # -OR-
  #
  # Match an empty line
  pattern = /(.{1,#{line_width}})(?:[^\S\n]+\n?|\n*\Z|\n)|\n/
  text.gsub(pattern, "\\1#{break_sequence}").chomp!(break_sequence)
end