Form-O-Fill: Fill only empty fields

fill_only_empty_fields.js

var rules = [{
  url: /all-types/,
  name: "Just fill empty fields",
  fields: [{
    "selector": "input[type=text]",
    "value": function($e) {
      return (!$e.val() ? "use this" : null);
    }
  },{
    "selector": "textarea",
    "value": function($e) {
      return (!$e.val() ? "use this" : null);
    }
  }]
}
];