diff --git a/src/ui-switch.component.ts b/src/ui-switch.component.ts
index 32a11c5..1ccb99d 100644
--- a/src/ui-switch.component.ts
+++ b/src/ui-switch.component.ts
@@ -148,7 +148,7 @@ export class UiSwitchComponent implements ControlValueAccessor {
   defaultBgColor: string = '#fff';
   defaultBoColor: string = '#dfdfdf';
 
-  getColor(flag) {
+  getColor(flag?:string) {
     if (flag === 'borderColor') return this.defaultBoColor;
     if (flag === 'switchColor') {
       if (this.reverse) return !this.checked ? this.switchColor : this.switchOffColor || this.switchColor;