feat: customizable start/end labels for range time input

When `selectsRange` is combined with `showTimeInput`, the two time inputs
had hardcoded "(Start)" / "(End)" suffixes appended to
`timeInputLabel`, with no way to override them.

Add `timeInputStartLabel` and `timeInputEndLabel` props. When provided,
each replaces the corresponding caption entirely; otherwise the existing
`"<timeInputLabel> (Start/End)"` behavior is unchanged. Single (non-range)
mode is unaffected.

Includes a docs-site example and tests covering default behaviour,
per-side fallback, and precedence over `timeInputLabel`.

Fixes #6280

Author: balajis-qb

docs-site/src/components/Examples/config.tsx

@@ -62,6 +62,7 @@ import Inline from "../../examples/ts/inline?raw";
 import InlineDisabled from "../../examples/ts/disabledInline?raw";
 import InlineVisible from "../../examples/ts/inlineVisible?raw";
 import TimeInput from "../../examples/ts/timeInput?raw";
+import RangeTimeInputLabels from "../../examples/ts/rangeTimeInputLabels?raw";
 import Locale from "../../examples/ts/locale?raw";
 import LocaleWithTime from "../../examples/ts/localeWithTime?raw";
 import LocaleWithoutGlobalVariable from "../../examples/ts/localeWithoutGlobalVariable?raw";
@@ -370,6 +371,10 @@ export const EXAMPLE_CONFIG: IExampleConfig[] = [
     title: "Input Time",
     component: TimeInput,
   },
+  {
+    title: "Input Time with Range (custom start/end labels)",
+    component: RangeTimeInputLabels,
+  },
   {
     title: "Locale",
     component: Locale,

docs-site/src/examples/ts/rangeTimeInputLabels.tsx

@@ -0,0 +1,26 @@
+const RangeTimeInputLabels = () => {
+  const [startDate, setStartDate] = useState<Date | null>(new Date());
+  const [endDate, setEndDate] = useState<Date | null>(null);
+
+  const onChange = (dates: [Date | null, Date | null]) => {
+    const [start, end] = dates;
+    setStartDate(start);
+    setEndDate(end);
+  };
+
+  return (
+    <DatePicker
+      selected={startDate}
+      onChange={onChange}
+      startDate={startDate}
+      endDate={endDate}
+      selectsRange
+      showTimeInput
+      timeInputStartLabel="Start time"
+      timeInputEndLabel="End time"
+      dateFormat="MM/dd/yyyy h:mm aa"
+    />
+  );
+};
+
+render(RangeTimeInputLabels);

src/calendar.tsx

@@ -223,6 +223,8 @@ type CalendarProps = React.PropsWithChildren<
       onTimeChange?: (time: Date, modifyDateType?: "start" | "end") => void;
       timeFormat?: TimeProps["format"];
       timeIntervals?: TimeProps["intervals"];
+      timeInputStartLabel?: string;
+      timeInputEndLabel?: string;
     } & (
       | ({
           showMonthYearDropdown: true;
@@ -1212,7 +1214,10 @@ export default class Calendar extends Component<CalendarProps, CalendarState> {
             onChange={(time: Date) => {
               this.props.onTimeChange?.(time, "start");
             }}
-            timeInputLabel={(this.props.timeInputLabel ?? "Time") + " (Start)"}
+            timeInputLabel={
+              this.props.timeInputStartLabel ??
+              (this.props.timeInputLabel ?? "Time") + " (Start)"
+            }
           />
           <InputTime
             {...Calendar.defaultProps}
@@ -1222,7 +1227,10 @@ export default class Calendar extends Component<CalendarProps, CalendarState> {
             onChange={(time: Date) => {
               this.props.onTimeChange?.(time, "end");
             }}
-            timeInputLabel={(this.props.timeInputLabel ?? "Time") + " (End)"}
+            timeInputLabel={
+              this.props.timeInputEndLabel ??
+              (this.props.timeInputLabel ?? "Time") + " (End)"
+            }
           />
         </>
       );

src/test/datepicker_test.test.tsx

@@ -6821,6 +6821,124 @@ describe("DatePicker", () => {
       expect(timeInputs[0]?.value).toBe("");
       expect(timeInputs[1]?.value).toBe("");
     });
+
+    describe("timeInputStartLabel / timeInputEndLabel props (#6280)", () => {
+      const rangeStart = newDate("2024-01-15 09:00:00");
+      const rangeEnd = newDate("2024-01-20 14:30:00");
+
+      const captionsOf = (container: HTMLElement) =>
+        Array.from(
+          container.querySelectorAll(".react-datepicker-time__caption"),
+        ).map((n) => n.textContent);
+
+      it("defaults to the hardcoded English suffixes", () => {
+        const { container } = render(
+          <DatePicker
+            selectsRange
+            startDate={rangeStart}
+            endDate={rangeEnd}
+            onChange={jest.fn()}
+            showTimeInput
+            inline
+          />,
+        );
+        expect(captionsOf(container)).toEqual(["Time (Start)", "Time (End)"]);
+      });
+
+      it("appends the suffixes to a custom timeInputLabel (existing behavior)", () => {
+        const { container } = render(
+          <DatePicker
+            selectsRange
+            startDate={rangeStart}
+            endDate={rangeEnd}
+            onChange={jest.fn()}
+            showTimeInput
+            timeInputLabel="Uhrzeit"
+            inline
+          />,
+        );
+        expect(captionsOf(container)).toEqual([
+          "Uhrzeit (Start)",
+          "Uhrzeit (End)",
+        ]);
+      });
+
+      it("replaces each caption entirely when the new props are provided", () => {
+        const { container } = render(
+          <DatePicker
+            selectsRange
+            startDate={rangeStart}
+            endDate={rangeEnd}
+            onChange={jest.fn()}
+            showTimeInput
+            timeInputStartLabel="Startzeit"
+            timeInputEndLabel="Endzeit"
+            inline
+          />,
+        );
+        expect(captionsOf(container)).toEqual(["Startzeit", "Endzeit"]);
+      });
+
+      it("overrides timeInputLabel + suffix when both are set", () => {
+        const { container } = render(
+          <DatePicker
+            selectsRange
+            startDate={rangeStart}
+            endDate={rangeEnd}
+            onChange={jest.fn()}
+            showTimeInput
+            timeInputLabel="Uhrzeit"
+            timeInputStartLabel="Von"
+            timeInputEndLabel="Bis"
+            inline
+          />,
+        );
+        expect(captionsOf(container)).toEqual(["Von", "Bis"]);
+      });
+
+      it("falls back per-side when only one of the two props is set", () => {
+        const { container: c1 } = render(
+          <DatePicker
+            selectsRange
+            startDate={rangeStart}
+            endDate={rangeEnd}
+            onChange={jest.fn()}
+            showTimeInput
+            timeInputStartLabel="Von"
+            inline
+          />,
+        );
+        expect(captionsOf(c1)).toEqual(["Von", "Time (End)"]);
+
+        const { container: c2 } = render(
+          <DatePicker
+            selectsRange
+            startDate={rangeStart}
+            endDate={rangeEnd}
+            onChange={jest.fn()}
+            showTimeInput
+            timeInputEndLabel="Bis"
+            inline
+          />,
+        );
+        expect(captionsOf(c2)).toEqual(["Time (Start)", "Bis"]);
+      });
+
+      it("does not affect single (non-range) mode", () => {
+        const { container } = render(
+          <DatePicker
+            selected={rangeStart}
+            onChange={jest.fn()}
+            showTimeInput
+            timeInputStartLabel="Startzeit"
+            timeInputEndLabel="Endzeit"
+            timeInputLabel="Uhrzeit"
+            inline
+          />,
+        );
+        expect(captionsOf(container)).toEqual(["Uhrzeit"]);
+      });
+    });
   });
 
   describe("Critical functions coverage - best in class", () => {