Add scrollIntoView to fragment instances

fixtures/dom/src/components/fixtures/fragment-refs/FocusCase.js

@@ -3,7 +3,7 @@ import Fixture from '../../Fixture';
 
 const React = window.React;
 
-const {Fragment, useEffect, useRef, useState} = React;
+const {Fragment, useRef} = React;
 
 export default function FocusCase() {
   const fragmentRef = useRef(null);

fixtures/dom/src/components/fixtures/fragment-refs/GetClientRectsCase.js

@@ -2,7 +2,7 @@ import TestCase from '../../TestCase';
 import Fixture from '../../Fixture';
 
 const React = window.React;
-const {Fragment, useEffect, useRef, useState} = React;
+const {Fragment, useRef, useState} = React;
 
 export default function GetClientRectsCase() {
   const fragmentRef = useRef(null);

fixtures/dom/src/components/fixtures/fragment-refs/ScrollIntoViewCase.js

@@ -0,0 +1,184 @@
+import TestCase from '../../TestCase';
+import Fixture from '../../Fixture';
+import ScrollIntoViewCaseComplex from './ScrollIntoViewCaseComplex';
+import ScrollIntoViewCaseSimple from './ScrollIntoViewCaseSimple';
+import ScrollIntoViewTargetElement from './ScrollIntoViewTargetElement';
+
+const React = window.React;
+const {Fragment, useRef, useState, useEffect} = React;
+const ReactDOM = window.ReactDOM;
+
+function Controls({
+  alignToTop,
+  setAlignToTop,
+  scrollVertical,
+  exampleType,
+  setExampleType,
+}) {
+  return (
+    <div>
+      <label>
+        Example Type:
+        <select
+          value={exampleType}
+          onChange={e => setExampleType(e.target.value)}>
+          <option value="simple">Simple</option>
+          <option value="multiple">Multiple Scroll Containers</option>
+          <option value="horizontal">Horizontal</option>
+          <option value="empty">Empty Fragment</option>
+        </select>
+      </label>
+      <div>
+        <label>
+          Align to Top:
+          <input
+            type="checkbox"
+            checked={alignToTop}
+            onChange={e => setAlignToTop(e.target.checked)}
+          />
+        </label>
+      </div>
+      <div>
+        <button onClick={scrollVertical}>scrollIntoView()</button>
+      </div>
+    </div>
+  );
+}
+
+export default function ScrollIntoViewCase() {
+  const [exampleType, setExampleType] = useState('simple');
+  const [alignToTop, setAlignToTop] = useState(true);
+  const [caseInViewport, setCaseInViewport] = useState(false);
+  const fragmentRef = useRef(null);
+  const testCaseRef = useRef(null);
+  const noChildRef = useRef(null);
+  const scrollContainerRef = useRef(null);
+
+  const scrollVertical = () => {
+    fragmentRef.current.experimental_scrollIntoView(alignToTop);
+  };
+
+  const scrollVerticalNoChildren = () => {
+    noChildRef.current.experimental_scrollIntoView(alignToTop);
+  };
+
+  useEffect(() => {
+    const observer = new IntersectionObserver(entries => {
+      entries.forEach(entry => {
+        if (entry.isIntersecting) {
+          setCaseInViewport(true);
+        } else {
+          setCaseInViewport(false);
+        }
+      });
+    });
+    testCaseRef.current.observeUsing(observer);
+
+    const lastRef = testCaseRef.current;
+    return () => {
+      lastRef.unobserveUsing(observer);
+      observer.disconnect();
+    };
+  });
+
+  return (
+    <Fragment ref={testCaseRef}>
+      <TestCase title="ScrollIntoView">
+        <TestCase.Steps>
+          <li>Toggle alignToTop and click the buttons to scroll</li>
+        </TestCase.Steps>
+        <TestCase.ExpectedResult>
+          <p>When the Fragment has children:</p>
+          <p>
+            In order to handle the case where children are split between
+            multiple scroll containers, we call scrollIntoView on each child in
+            reverse order.
+          </p>
+          <p>When the Fragment does not have children:</p>
+          <p>
+            The Fragment still represents a virtual space. We can scroll to the
+            nearest edge by selecting the host sibling before if
+            alignToTop=false, or after if alignToTop=true|undefined. We'll fall
+            back to the other sibling or parent in the case that the preferred
+            sibling target doesn't exist.
+          </p>
+        </TestCase.ExpectedResult>
+        <Fixture>
+          <Fixture.Controls>
+            <Controls
+              alignToTop={alignToTop}
+              setAlignToTop={setAlignToTop}
+              scrollVertical={scrollVertical}
+              exampleType={exampleType}
+              setExampleType={setExampleType}
+            />
+          </Fixture.Controls>
+          {exampleType === 'simple' && (
+            <Fragment ref={fragmentRef}>
+              <ScrollIntoViewCaseSimple />
+            </Fragment>
+          )}
+          {exampleType === 'horizontal' && (
+            <div
+              style={{
+                display: 'flex',
+                overflowX: 'auto',
+                flexDirection: 'row',
+                border: '1px solid #ccc',
+                padding: '1rem 10rem',
+                marginBottom: '1rem',
+                width: '100%',
+                whiteSpace: 'nowrap',
+                justifyContent: 'space-between',
+              }}>
+              <Fragment ref={fragmentRef}>
+                <ScrollIntoViewCaseSimple />
+              </Fragment>
+            </div>
+          )}
+          {exampleType === 'multiple' && (
+            <Fragment>
+              <div
+                style={{
+                  height: '50vh',
+                  overflowY: 'auto',
+                  border: '1px solid black',
+                  marginBottom: '1rem',
+                }}
+                ref={scrollContainerRef}
+              />
+              <Fragment ref={fragmentRef}>
+                <ScrollIntoViewCaseComplex
+                  caseInViewport={caseInViewport}
+                  scrollContainerRef={scrollContainerRef}
+                />
+              </Fragment>
+            </Fragment>
+          )}
+          {exampleType === 'empty' && (
+            <Fragment>
+              <ScrollIntoViewTargetElement
+                color="lightyellow"
+                id="ABOVE EMPTY FRAGMENT"
+              />
+              <Fragment ref={fragmentRef}></Fragment>
+              <ScrollIntoViewTargetElement
+                color="lightblue"
+                id="BELOW EMPTY FRAGMENT"
+              />
+            </Fragment>
+          )}
+          <Fixture.Controls>
+            <Controls
+              alignToTop={alignToTop}
+              setAlignToTop={setAlignToTop}
+              scrollVertical={scrollVertical}
+              exampleType={exampleType}
+              setExampleType={setExampleType}
+            />
+          </Fixture.Controls>
+        </Fixture>
+      </TestCase>
+    </Fragment>
+  );
+}

fixtures/dom/src/components/fixtures/fragment-refs/ScrollIntoViewCaseComplex.js

@@ -0,0 +1,50 @@
+import ScrollIntoViewTargetElement from './ScrollIntoViewTargetElement';
+
+const React = window.React;
+const {Fragment, useRef, useState, useEffect} = React;
+const ReactDOM = window.ReactDOM;
+
+export default function ScrollIntoViewCaseComplex({
+  caseInViewport,
+  scrollContainerRef,
+}) {
+  const [didMount, setDidMount] = useState(false);
+  // Hack to portal child into the scroll container
+  // after the first render. This is to simulate a case where
+  // an item is portaled into another scroll container.
+  useEffect(() => {
+    if (!didMount) {
+      setDidMount(true);
+    }
+  }, []);
+  return (
+    <Fragment>
+      {caseInViewport && (
+        <div
+          style={{position: 'fixed', top: 0, backgroundColor: 'red'}}
+          id="header">
+          Fixed header
+        </div>
+      )}
+      {didMount &&
+        ReactDOM.createPortal(
+          <ScrollIntoViewTargetElement color="red" id="FROM_PORTAL" />,
+          scrollContainerRef.current
+        )}
+      <ScrollIntoViewTargetElement color="lightgreen" id="A" />
+      <ScrollIntoViewTargetElement color="lightcoral" id="B" />
+      <ScrollIntoViewTargetElement color="lightblue" id="C" />
+      {caseInViewport && (
+        <div
+          style={{
+            position: 'fixed',
+            bottom: 0,
+            backgroundColor: 'purple',
+          }}
+          id="footer">
+          Fixed footer
+        </div>
+      )}
+    </Fragment>
+  );
+}

fixtures/dom/src/components/fixtures/fragment-refs/ScrollIntoViewCaseSimple.js

@@ -0,0 +1,14 @@
+import ScrollIntoViewTargetElement from './ScrollIntoViewTargetElement';
+
+const React = window.React;
+const {Fragment} = React;
+
+export default function ScrollIntoViewCaseSimple() {
+  return (
+    <Fragment>
+      <ScrollIntoViewTargetElement color="lightyellow" id="SCROLLABLE-1" />
+      <ScrollIntoViewTargetElement color="lightpink" id="SCROLLABLE-2" />
+      <ScrollIntoViewTargetElement color="lightcyan" id="SCROLLABLE-3" />
+    </Fragment>
+  );
+}

fixtures/dom/src/components/fixtures/fragment-refs/ScrollIntoViewTargetElement.js

@@ -0,0 +1,18 @@
+const React = window.React;
+
+export default function ScrollIntoViewTargetElement({color, id, top}) {
+  return (
+    <div
+      id={id}
+      style={{
+        height: 500,
+        minWidth: 300,
+        backgroundColor: color,
+        marginTop: top ? '50vh' : 0,
+        marginBottom: 100,
+        flexShrink: 0,
+      }}>
+      {id}
+    </div>
+  );
+}

fixtures/dom/src/components/fixtures/fragment-refs/index.js

@@ -5,6 +5,7 @@ import IntersectionObserverCase from './IntersectionObserverCase';
 import ResizeObserverCase from './ResizeObserverCase';
 import FocusCase from './FocusCase';
 import GetClientRectsCase from './GetClientRectsCase';
+import ScrollIntoViewCase from './ScrollIntoViewCase';
 
 const React = window.React;
 
@@ -17,6 +18,7 @@ export default function FragmentRefsPage() {
       <ResizeObserverCase />
       <FocusCase />
       <GetClientRectsCase />
+      <ScrollIntoViewCase />
     </FixtureSet>
   );
 }

fixtures/dom/src/index.js

@@ -2,14 +2,23 @@ import './polyfills';
 import loadReact, {isLocal} from './react-loader';
 
 if (isLocal()) {
-  Promise.all([import('react'), import('react-dom/client')])
-    .then(([React, ReactDOMClient]) => {
-      if (React === undefined || ReactDOMClient === undefined) {
+  Promise.all([
+    import('react'),
+    import('react-dom'),
+    import('react-dom/client'),
+  ])
+    .then(([React, ReactDOM, ReactDOMClient]) => {
+      if (
+        React === undefined ||
+        ReactDOM === undefined ||
+        ReactDOMClient === undefined
+      ) {
         throw new Error(
           'Unable to load React. Build experimental and then run `yarn dev` again'
         );
       }
       window.React = React;
+      window.ReactDOM = ReactDOM;
       window.ReactDOMClient = ReactDOMClient;
     })
     .then(() => import('./components/App'))