diff --git a/src/app/components/byline/byline.js b/src/app/components/byline/byline.js
deleted file mode 100644
index 0eb820402..000000000
--- a/src/app/components/byline/byline.js
+++ /dev/null
@@ -1,16 +0,0 @@
-import React from 'react';
-import './byline.scss';
-import {formatDateForBlog} from '~/helpers/data';
-
-export default function Byline({date, author, source=undefined}) {
-    return (
-        <div className="byline">
-            {
-                source ?
-                    <span className="source">{source}</span> :
-                    <span className="author">{author}</span>
-            }
-            <span className="date">{formatDateForBlog(date)}</span>
-        </div>
-    );
-}
diff --git a/src/app/components/byline/byline.tsx b/src/app/components/byline/byline.tsx
new file mode 100644
index 000000000..c94380c92
--- /dev/null
+++ b/src/app/components/byline/byline.tsx
@@ -0,0 +1,24 @@
+import React from 'react';
+import './byline.scss';
+import {formatDateForBlog} from '~/helpers/data';
+
+export default function Byline({
+    date,
+    author,
+    source
+}: {
+    date: string;
+    author: string;
+    source?: string;
+}) {
+    return (
+        <div className="byline">
+            {source ? (
+                <span className="source">{source}</span>
+            ) : (
+                <span className="author">{author}</span>
+            )}
+            <span className="date">{formatDateForBlog(date)}</span>
+        </div>
+    );
+}
diff --git a/src/app/components/carousel/carousel.js b/src/app/components/carousel/carousel.tsx
similarity index 51%
rename from src/app/components/carousel/carousel.js
rename to src/app/components/carousel/carousel.tsx
index 30d463de6..49fa69f59 100644
--- a/src/app/components/carousel/carousel.js
+++ b/src/app/components/carousel/carousel.tsx
@@ -1,15 +1,28 @@
 import React from 'react';
-import {Carousel as BaseCarousel, CarouselButton, CarouselItem, CarouselScroller} from 'react-aria-carousel';
+import {
+    Carousel as BaseCarousel,
+    CarouselButton,
+    CarouselItem,
+    CarouselScroller
+} from 'react-aria-carousel';
 import {FontAwesomeIcon} from '@fortawesome/react-fontawesome';
 import {faChevronLeft} from '@fortawesome/free-solid-svg-icons/faChevronLeft';
 import {faChevronRight} from '@fortawesome/free-solid-svg-icons/faChevronRight';
 import './carousel.scss';
 
+// FrameChanger was part of the homegrown carousel, but react-aria-carousel has such items
+// built-in, so this is only used by pdf-unit (body-units) now. Might be able to use
+// CarouselButton (from react-aria-carousel) for that.
 export function FrameChanger({
     chevronDirection,
     onClick,
-    hoverText = '',
-    disable = false
+    hoverText,
+    disable
+}: {
+    chevronDirection: 'left' | 'right';
+    onClick: React.MouseEventHandler<HTMLButtonElement>;
+    hoverText?: string;
+    disable?: boolean;
 }) {
     const icon = {
         left: faChevronLeft,
@@ -22,25 +35,23 @@ export function FrameChanger({
 
     return (
         <button
-            type='button'
+            type="button"
             className={`frame-changer ${chevronDirection}`}
             onClick={onClick}
             disabled={disable}
             aria-label={label}
         >
             <FontAwesomeIcon icon={icon} />
-            {hoverText && <span className='hover-text'>{hoverText}</span>}
+            {hoverText && <span className="hover-text">{hoverText}</span>}
         </button>
     );
 }
 
-function HoverText({which, thing}) {
+function HoverText({which, thing}: {which: string; thing: string}) {
     if (!thing) {
         return null;
     }
-    return (
-        <span className='hover-text'>{`${which} ${thing}`}</span>
-    );
+    return <span className="hover-text">{`${which} ${thing}`}</span>;
 }
 
 export default function Carousel({
@@ -48,27 +59,29 @@ export default function Carousel({
     children,
     hoverTextThing,
     ref
-}) {
-    const slides = React.useMemo(
-        () => {
-            return React.Children.toArray(children).map((child, i) =>
-            <CarouselItem index={i} key={i}>{child}</CarouselItem>);
-        },
-        [children]
-    );
+}: React.PropsWithChildren<{
+    atATime?: number;
+    hoverTextThing: string;
+    ref?: Parameters<typeof BaseCarousel>[0]['ref'];
+}>) {
+    const slides = React.useMemo(() => {
+        return React.Children.toArray(children).map((child, i) => (
+            <CarouselItem index={i} key={i}>
+                {child}
+            </CarouselItem>
+        ));
+    }, [children]);
 
     return (
         <BaseCarousel className="carousel" itemsPerPage={atATime} ref={ref}>
-            <CarouselScroller className="scroller">
-                {slides}
-            </CarouselScroller>
+            <CarouselScroller className="scroller">{slides}</CarouselScroller>
             <CarouselButton dir="prev" className="frame-changer left">
                 <FontAwesomeIcon icon={faChevronLeft} />
-                <HoverText which='Previous' thing={hoverTextThing} />
+                <HoverText which="Previous" thing={hoverTextThing} />
             </CarouselButton>
             <CarouselButton dir="next" className="frame-changer right">
                 <FontAwesomeIcon icon={faChevronRight} />
-                <HoverText which='Next' thing={hoverTextThing} />
+                <HoverText which="Next" thing={hoverTextThing} />
             </CarouselButton>
         </BaseCarousel>
     );
diff --git a/src/app/pages/subjects/new/specific/components/carousel-section.tsx b/src/app/pages/subjects/new/specific/components/carousel-section.tsx
index 5a4da5665..ec6cdfe35 100644
--- a/src/app/pages/subjects/new/specific/components/carousel-section.tsx
+++ b/src/app/pages/subjects/new/specific/components/carousel-section.tsx
@@ -14,7 +14,7 @@ export default function CarouselSection({
     minWidth: number;
 }>) {
     const {innerWidth} = useWindowContext();
-    const ref = React.useRef<{base: HTMLDivElement}>();
+    const ref = React.useRef<HTMLDivElement & {base: Element}>(null);
     const [atATime, setAtATime] = React.useState(1);
 
     React.useEffect(
diff --git a/src/app/pages/webinars/webinar-cards/webinar-grid.tsx b/src/app/pages/webinars/webinar-cards/webinar-grid.tsx
index 656611cb9..c2652eb4c 100644
--- a/src/app/pages/webinars/webinar-cards/webinar-grid.tsx
+++ b/src/app/pages/webinars/webinar-cards/webinar-grid.tsx
@@ -28,7 +28,7 @@ function PastWebinar({data}: {data: Webinar}) {
     return (
         <div className='card past'>
             <h3>{data.title}</h3>
-            <Byline author={data.speakers} date={data.start} />
+            <Byline author={data.speakers} date={data.start.toDateString()} />
             <div>{data.description}</div>
             <LinkWithChevron href={data.registrationUrl}>
                 {data.registrationLinkText}
diff --git a/test/src/components/carousel.test.tsx b/test/src/components/carousel.test.tsx
new file mode 100644
index 000000000..fdedddf28
--- /dev/null
+++ b/test/src/components/carousel.test.tsx
@@ -0,0 +1,70 @@
+import React from 'react';
+import {render, screen} from '@testing-library/preact';
+import userEvent from '@testing-library/user-event';
+import Carousel, { FrameChanger } from '~/components/carousel/carousel';
+
+const mockReactCarousel = jest.fn();
+const mockCarouselButton = jest.fn();
+
+// react-aria-carousel does not play nice with Jest
+jest.mock('react-aria-carousel', () => ({
+    Carousel: ({children}: React.PropsWithChildren<object>) => mockReactCarousel({children}),
+    CarouselButton: ({children}: React.PropsWithChildren<object>) => mockCarouselButton({children})
+}));
+
+describe('carousel', () => {
+    mockReactCarousel.mockImplementation(({children}: React.PropsWithChildren<object>) => {
+        return <div>{children}</div>;
+    });
+    mockCarouselButton.mockImplementation(({children}: React.PropsWithChildren<object>) => {
+        return <div>{children}</div>;
+    });
+    it('renders with hover text', () => {
+        render(
+            <Carousel hoverTextThing='some hover text' atATime={2}>
+                <div>one</div>
+                <div>two</div>
+                <div>three</div>
+                <div>four</div>
+            </Carousel>
+        );
+        expect(document.querySelectorAll('.hover-text')).toHaveLength(2);
+    });
+    it('renders with empty hover text, default atATime', () => {
+        render(
+            <Carousel hoverTextThing=''>
+                <div>one</div>
+                <div>two</div>
+                <div>three</div>
+                <div>four</div>
+            </Carousel>
+        );
+        expect(document.querySelectorAll('.hover-text')).toHaveLength(0);
+    });
+});
+
+describe('frame-changer', () => {
+    const user = userEvent.setup();
+
+    it('renders disabled', async () => {
+        const onclick = jest.fn();
+
+        render(<FrameChanger chevronDirection='left' onClick={onclick} disable />);
+        const b = screen.getByRole('button');
+
+        expect(b.getAttribute('disabled')).toBe("");
+        await user.click(b);
+        expect(onclick).not.toHaveBeenCalled();
+    });
+    it('handles clicks when not disabled', async () => {
+        const onclick = jest.fn();
+
+        render(<FrameChanger chevronDirection='left' onClick={onclick} hoverText='some hover text' />);
+        const b = screen.getByRole('button');
+
+        expect(b.getAttribute('disabled')).not.toBe(true);
+        await user.click(b);
+        expect(onclick).toHaveBeenCalled();
+        expect(b.querySelector('.hover-text')?.textContent).toBe('some hover text');
+    });
+});
diff --git a/tsconfig.json b/tsconfig.json
index b0fb9327a..c71c65cb1 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -3,11 +3,12 @@
       "allowJs": true,
       // "checkJs": true,
       "target": "es6",
-      "module": "commonjs",
+      "module": "ES2020",
       "jsx": "react",
       "outDir": "./dist",
       "strict": true,
       "esModuleInterop": true,
+      "moduleResolution": "bundler",
       "paths": {
         "~*": ["./src/app/*"]
       }