Fix for Slider to support Form properly

examples/bpk-component-slider/examples.js

@@ -69,6 +69,7 @@ class SliderContainer extends Component {
           value={this.state.value}
           ariaLabel={['minimum', 'maximum']}
           ariaValuetext={[this.state.value[0], this.state.value[1]]}
+          inputProps={[{name: 'min'}, {name: 'max'}]}
         />
         <br />
       </div>

packages/bpk-component-slider/src/BpkSlider.tsx

@@ -15,10 +15,18 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+import {
+  forwardRef,
+  useRef,
+  useEffect,
+  type ComponentPropsWithRef,
+} from 'react';
 
+import { useComposedRefs } from '@radix-ui/react-compose-refs';
 import * as Slider from '@radix-ui/react-slider';
+import { usePrevious } from '@radix-ui/react-use-previous';
 
-import { cssModules, isRTL } from '../../bpk-react-utils';
+import { cssModules, isRTL, setNativeValue } from '../../bpk-react-utils';
 
 import STYLES from './BpkSlider.module.scss';
 
@@ -34,12 +42,14 @@ export type Props = {
   value: number[] | number;
   ariaLabel: string[];
   ariaValuetext?: string[];
+  inputProps?: [{ [key: string]: any }];
   [rest: string]: any;
 };
 
 const BpkSlider = ({
   ariaLabel,
   ariaValuetext,
+  inputProps,
   max,
   min,
   minDistance,
@@ -93,10 +103,54 @@ const BpkSlider = ({
           aria-valuetext={ariaValuetext ? ariaValuetext[index] : val.toString()}
           className={getClassName('bpk-slider__thumb')}
           aria-valuenow={currentValue[index]}
-        />
+          asChild
+        >
+          {/* custom thumb with child input */}
+          <span>
+            <BubbleInput value={currentValue[index]} {...inputProps} />
+          </span>
+        </Slider.Thumb>
       ))}
     </Slider.Root>
   );
 };
 
+// Work around until radix-ui/react-slider is updated to accept an inputRef prop https://github.com/radix-ui/primitives/pull/3033
+const BubbleInput = forwardRef(
+  (props: ComponentPropsWithRef<'input'>, forwardedRef) => {
+    const { value, ...inputProps } = props;
+    const ref = useRef<HTMLInputElement>();
+    const composedRefs = useComposedRefs(forwardedRef, ref);
+
+    const prevValue = usePrevious(value);
+
+    // Bubble value change to parents (e.g form change event)
+    useEffect(() => {
+      const input = ref.current!;
+      if (prevValue !== value) {
+        setNativeValue(input, `${value}`);
+      }
+    }, [prevValue, value]);
+
+    /**
+     * We purposefully do not use `type="hidden"` here otherwise forms that
+     * wrap it will not be able to access its value via the FormData API.
+     *
+     * We purposefully do not add the `value` attribute here to allow the value
+     * to be set programatically and bubble to any parent form `onChange` event.
+     * Adding the `value` will cause React to consider the programatic
+     * dispatch a duplicate and it will get swallowed.
+     */
+    return (
+      <input
+        style={{ display: 'none' }}
+        {...inputProps}
+        ref={composedRefs}
+        type="number"
+        defaultValue={value}
+      />
+    );
+  },
+);
+
 export default BpkSlider;

packages/package.json

@@ -24,7 +24,9 @@
   "dependencies": {
     "@floating-ui/react": "^0.26.12",
     "@popperjs/core": "^2.11.8",
+    "@radix-ui/react-compose-refs": "^1.1.0",
     "@radix-ui/react-slider": "^1.1.2",
+    "@radix-ui/react-use-previous": "^1.1.0",
     "@react-google-maps/api": "^2.19.3",
     "@skyscanner/bpk-foundations-web": "^18.1.0",
     "@skyscanner/bpk-svgs": "^19.3.0",