gistfile1.js

// original javascript
String.prototype.singleDiff = function(that) {
  var diff = '';
  var thatLength = that.length;
  for (var i = 0; i < thatLength; ++i) {
    if (this[i] != that[i]) {
      var regExEscape = this.substr(i).regExEscape().replace(/^\s+|^(&nbsp;)+/g, '');
      var re = new RegExp(regExEscape + '$', 'm');
      diff = that.substr(i).replace(re, '');
      break;
    }
  }

  return diff;
};

# coffeescript -- note that we have to use _i here, which seems really bad
String::singleDiff = (that) ->
  diff = ''
  for char in that
    if char != @[_i] # using _i is lame!
      re = new RegExp(@substr(_i).regExpEscape().replace(/^\s+|^(&nbsp;)+/g, '') + '$', 'm')
      diff = that.substr(_i).replace(re, '')
      break

  return diff


# other attempts and their results
for index in [0..that.length]
 -- for (index = 0, _ref = that.length; 0 <= _ref ? index <= _ref : index >= _ref; 0 <= _ref ? index++ : index--) { }

for char in that
 -- for (_i = 0, _len = that.length; _i < _len; _i++) {
      char = that[_i];
    }