widowless.js

// Inserts a non breaking space character between the last two words in each text block, to prevent widows
$('.selector').each(function() {
  var words = $(this).text().split(' ');
  var replacement = words[words.length - 2] + '\xA0' + words[words.length - 1];
  words.splice(words.length - 2, 1, replacement);
  words.pop();
  var updatedString = words.join(' ');
  $(this).text(updatedString);
});