1 files changed, 143 insertions, 0 deletions
diff --git a/shared/components/src/utils/scrollByPolyfill.ts b/shared/components/src/utils/scrollByPolyfill.ts
new file mode 100644
index 0000000..1a73a4f
--- /dev/null
+++ b/shared/components/src/utils/scrollByPolyfill.ts
@@ -0,0 +1,143 @@
+// COPIED FROM
+// https://github.pie.apple.com/amp-ui/ember-ui-media-shelf/blob/580ff07a546771bce8b3d85494c6268860e97215/addon/-private/scroll-by-polyfill.js
+
+const SCROLL_TIME = 468;
+const Element =
+    typeof window !== 'undefined' ? window.HTMLElement || window.Element : null;
+
+let originalScrollBy;
+
+/**
+ * returns result of applying ease math function to a number
+ * @method ease
+ * @param {Number} k
+ * @returns {Number}
+ */
+function ease(k: number): number {
+    return 0.5 * (1 - Math.cos(Math.PI * k));
+}
+
+// define timing method
+const now: () => number =
+    typeof window !== 'undefined' && window?.performance?.now
+        ? window.performance.now.bind(window.performance)
+        : Date.now;
+
+/**
+ * changes scroll position inside an element
+ * @method scrollElement
+ * @param {Number} x
+ * @returns {undefined}
+ */
+function scrollElement(x: number): void {
+    this.scrollLeft = x;
+}
+
+/**
+ * self invoked function that, given a context, steps through scrolling
+ * @method step
+ * @param {Object} context
+ * @returns {undefined}
+ */
+type Context = {
+    startTime: number;
+    startX: number;
+    x: number;
+    method: (x: number) => void;
+    scrollable: HTMLElement;
+};
+function step(context: Context): void {
+    const time = now();
+    let elapsed = (time - context.startTime) / SCROLL_TIME;
+
+    // avoid elapsed times higher than one
+    elapsed = Math.min(1, elapsed);
+
+    // apply easing to elapsed time
+    const value = ease(elapsed);
+
+    const currentX = context.startX + (context.x - context.startX) * value;
+
+    context.method.call(context.scrollable, currentX);
+
+    // scroll more if we have not reached our destination
+    if (currentX !== context.x) {
+        window.requestAnimationFrame(step.bind(window, context));
+    }
+}
+
+/**
+ * scrolls window or element with a smooth behavior
+ * @method smoothScroll
+ * @param {Object|Node} el
+ * @param {Number} x
+ * @returns {undefined}
+ */
+function smoothScroll(el: HTMLElement, x: number): void {
+    const startTime = now();
+    // define scroll context
+    const startX = el.scrollLeft;
+    const method = scrollElement;
+
+    // scroll looping over a frame
+    step({
+        scrollable: el,
+        method,
+        startTime,
+        startX,
+        x,
+    });
+}
+
+let polyfillHasRun = false;
+/**
+ * ripped partially from https://github.com/iamdustan/smoothscroll/blob/master/src/smoothscroll.js
+ * Only polyfill horizontal scroll space to avoid unexpected behaviour in parent apps
+ *
+ * @method scrollByPolyfill
+ */
+export default function scrollByPolyfill(): void {
+    // return if scroll behavior is supported
+    if ('scrollBehavior' in document.documentElement.style || polyfillHasRun) {
+        return;
+    }
+
+    // if prefers-reduce-motion && need polyfill, navigate shelf immediately without easing
+    const motionMediaQuery = window.matchMedia(
+        '(prefers-reduced-motion: reduce)',
+    );
+    function addScrollByToProto() {
+        if (motionMediaQuery.matches) {
+            if (originalScrollBy) {
+                Element.prototype.scrollBy = originalScrollBy;
+            }
+            return;
+        }
+
+        function scrollByPoly(options: ScrollToOptions): void;
+        function scrollByPoly(x: number, _y: number): void;
+        // eslint-disable-next-line @typescript-eslint/no-unused-vars
+        function scrollByPoly(
+            paramOne: number | ScrollToOptions,
+            _paramTwo?: number,
+        ): void {
+            let xValue = 0;
+            if (typeof paramOne === 'number') {
+                xValue = paramOne;
+            } else if (typeof paramOne === 'object') {
+                xValue = paramOne.left || 0;
+            }
+
+            const moveByX = this.scrollLeft + xValue;
+            smoothScroll(this, moveByX);
+        }
+
+        originalScrollBy = Element.prototype.scrollBy;
+        Element.prototype.scrollBy = scrollByPoly;
+    }
+
+    motionMediaQuery.addListener(addScrollByToProto);
+
+    addScrollByToProto();
+    polyfillHasRun = true;
+}