A poor man's helper for tracking dirty fields.

tracks_dirty_fields.js

var tracksDirtyFields = (function($inputs) {
    var inputValue = function($input) {
          return $input.is(':checkbox,:radio') ? $input.is(':checked') : $input.val();
        },
        countFields = function() {
          return $(':input').length;
        },
        readFields = function() {
          return _({}).tap(function(values) {
            _($(':input')).each(function(input) {
              values[$(input).attr('name')] = inputValue($(input));
            });
          });
        },
        initialCount = countFields(),
        initialValues = readFields();
    return {
      isDirty: function() {
        return initialCount !== countFields() || !_(initialValues).isEqual(readFields());
      }
    };
  })();

//so at any point, you can check dirtiness with
tracksDirtyFields.isDirty()