Returns a GET-like serialisation string of the form values.

@api
@returns {string}
function getSerialisedData(){
    var data = this.getFormData();

    return data.length === 0 ? '' : '?' + data.map(function(f){
      return encodeURIComponent(f.name) + '=' + encodeURIComponent(f.value);
    }).join('&');
  }