code: function () {
              var $input;
              var id = this.inputId;
              var attrs =  this.addId ? { id : id, name: id } : {};
              var valForInput = this.getValueForInput();
              $input = Backbone.$('<' + this.elementType + '>');
              if (this.elementType === 'input') { attrs.type = 'text'; }
              if (this.placeholder) { attrs.placeholder = this.placeholder; }
              $input.attr(extend(attrs, this.inputAttrs));
              if (this.inputClass) { $input.attr('class', this.inputClass); }
              this.getInputWrapper().html($input);
              if (this._shouldSetValueOnInput(valForInput)) { $input.val(valForInput); }
              this.isDisabled = null;
              return this;
          }
docs: Renders the field input and places it in the wrapper in
  the element with the 'data-input' attribute
  @memberOf Backbone.fields.FieldView#
  @return {Backbone.fields.FieldView}