[Popper] Fix anchorEl prop types

docs/src/pages/components/popper/SimplePopper.js

@@ -12,7 +12,7 @@ const useStyles = makeStyles(theme => ({
   },
 }));
 
-function SimplePopper() {
+export default function SimplePopper() {
   const classes = useStyles();
   const [anchorEl, setAnchorEl] = React.useState(null);
 
@@ -21,7 +21,7 @@ function SimplePopper() {
   }
 
   const open = Boolean(anchorEl);
-  const id = open ? 'simple-popper' : null;
+  const id = open ? 'simple-popper' : undefined;
 
   return (
     <div>
@@ -40,5 +40,3 @@ function SimplePopper() {
     </div>
   );
 }
-
-export default SimplePopper;

docs/src/pages/components/popper/SimplePopper.tsx

@@ -0,0 +1,44 @@
+import React from 'react';
+import { makeStyles, Theme, createStyles } from '@material-ui/core/styles';
+import Popper from '@material-ui/core/Popper';
+import Typography from '@material-ui/core/Typography';
+import Button from '@material-ui/core/Button';
+import Fade from '@material-ui/core/Fade';
+import Paper from '@material-ui/core/Paper';
+
+const useStyles = makeStyles((theme: Theme) =>
+  createStyles({
+    typography: {
+      padding: theme.spacing(2),
+    },
+  }),
+);
+
+export default function SimplePopper() {
+  const classes = useStyles();
+  const [anchorEl, setAnchorEl] = React.useState<null | HTMLElement>(null);
+
+  function handleClick(event: React.MouseEvent<HTMLElement>) {
+    setAnchorEl(anchorEl ? null : event.currentTarget);
+  }
+
+  const open = Boolean(anchorEl);
+  const id = open ? 'simple-popper' : undefined;
+
+  return (
+    <div>
+      <Button aria-describedby={id} variant="contained" onClick={handleClick}>
+        Toggle Popper
+      </Button>
+      <Popper id={id} open={open} anchorEl={anchorEl} transition>
+        {({ TransitionProps }) => (
+          <Fade {...TransitionProps} timeout={350}>
+            <Paper>
+              <Typography className={classes.typography}>The content of the Popper.</Typography>
+            </Paper>
+          </Fade>
+        )}
+      </Popper>
+    </div>
+  );
+}

docs/src/pages/components/popper/popper.md

@@ -11,7 +11,7 @@ Some important features of the `Popper` component:
 
 - 🕷 Popper relies on the 3rd party library ([Popper.js](https://github.com/FezVrasta/popper.js)) for perfect positioning.
 - 💄 It's an alternative API to react-popper. It aims for simplicity.
-- 📦 [10 kB gzipped](/size-snapshot).
+- 📦 [10 kB gzipped](/size-snapshot) (7 kB from Popper.js).
 - The children is [`Portal`](/components/portal/) to the body of the document to avoid rendering problems.
 You can disable this behavior with `disablePortal`.
 - The scroll isn't blocked like with the [`Popover`](/components/popover/) component.

packages/material-ui/src/Popper/Popper.d.ts

@@ -19,7 +19,7 @@ export type PopperPlacementType =
 
 export interface PopperProps extends React.HTMLAttributes<HTMLDivElement> {
   transition?: boolean;
-  anchorEl?: null | Element | ReferenceObject | (() => Element);
+  anchorEl?: null | ReferenceObject | (() => ReferenceObject);
   children:
     | React.ReactNode
     | ((props: {

packages/material-ui/src/Popper/Popper.js

@@ -165,37 +165,46 @@ const Popper = React.forwardRef(function Popper(props, ref) {
 
 Popper.propTypes = {
   /**
-   * This is the DOM element, or a function that returns the DOM element,
+   * This is the reference element, or a function that returns the reference element,
    * that may be used to set the position of the popover.
    * The return value will passed as the reference object of the Popper
    * instance.
+   *
+   * The reference element should be an HTML Element instance or a referenceObject:
+   * https://popper.js.org/popper-documentation.html#referenceObject.
    */
   anchorEl: chainPropTypes(PropTypes.oneOfType([PropTypes.object, PropTypes.func]), props => {
     if (props.open) {
       const resolvedAnchorEl = getAnchorEl(props.anchorEl);
 
-      if (resolvedAnchorEl instanceof Element) {
-        const box = resolvedAnchorEl.getBoundingClientRect();
+      if (
+        !resolvedAnchorEl ||
+        typeof resolvedAnchorEl.clientWidth !== 'number' ||
+        typeof resolvedAnchorEl.clientHeight !== 'number' ||
+        typeof resolvedAnchorEl.getBoundingClientRect !== 'function'
+      ) {
+        return new Error(
+          [
+            'Material-UI: the `anchorEl` prop provided to the component is invalid.',
+            'It should be an HTML Element instance or a referenceObject:',
+            'https://popper.js.org/popper-documentation.html#referenceObject.',
+          ].join('\n'),
+        );
+      }
+
+      const box = resolvedAnchorEl.getBoundingClientRect();
 
-        if (
-          process.env.NODE_ENV !== 'test' &&
-          box.top === 0 &&
-          box.left === 0 &&
-          box.right === 0 &&
-          box.bottom === 0
-        ) {
-          return new Error(
-            [
-              'Material-UI: the `anchorEl` prop provided to the component is invalid.',
-              'The node element should be visible.',
-            ].join('\n'),
-          );
-        }
-      } else {
+      if (
+        process.env.NODE_ENV !== 'test' &&
+        box.top === 0 &&
+        box.left === 0 &&
+        box.right === 0 &&
+        box.bottom === 0
+      ) {
         return new Error(
           [
             'Material-UI: the `anchorEl` prop provided to the component is invalid.',
-            `It should be an Element instance but it's \`${resolvedAnchorEl}\` instead.`,
+            'The reference element should be visible.',
           ].join('\n'),
         );
       }

packages/material-ui/src/Popper/Popper.test.js

@@ -215,7 +215,7 @@ describe('<Popper />', () => {
     it('should warn if anchorEl is not valid', () => {
       mount(<Popper {...defaultProps} open anchorEl={null} />);
       assert.strictEqual(consoleErrorMock.callCount(), 1);
-      assert.include(consoleErrorMock.args()[0][0], 'It should be an Element instance');
+      assert.include(consoleErrorMock.args()[0][0], 'It should be an HTML Element instance');
     });
 
     // it('should warn if anchorEl is not visible', () => {

pages/api/popper.md

@@ -18,7 +18,7 @@ Poppers rely on the 3rd party library [Popper.js](https://github.com/FezVrasta/p
 
 | Name | Type | Default | Description |
 |:-----|:-----|:--------|:------------|
-| <span class="prop-name">anchorEl</span> | <span class="prop-type">union:&nbsp;object&nbsp;&#124;<br>&nbsp;func<br></span> |  | This is the DOM element, or a function that returns the DOM element, that may be used to set the position of the popover. The return value will passed as the reference object of the Popper instance. |
+| <span class="prop-name">anchorEl</span> | <span class="prop-type">union:&nbsp;object&nbsp;&#124;<br>&nbsp;func<br></span> |  | This is the reference element, or a function that returns the reference element, that may be used to set the position of the popover. The return value will passed as the reference object of the Popper instance.<br>The reference element should be an HTML Element instance or a referenceObject: https://popper.js.org/popper-documentation.html#referenceObject. |
 | <span class="prop-name required">children&nbsp;*</span> | <span class="prop-type">union:&nbsp;node&nbsp;&#124;<br>&nbsp;func<br></span> |  | Popper render function or node. |
 | <span class="prop-name">container</span> | <span class="prop-type">union:&nbsp;object&nbsp;&#124;<br>&nbsp;func<br></span> |  | A node, component instance, or function that returns either. The `container` will passed to the Modal component. By default, it uses the body of the anchorEl's top-level document object, so it's simply `document.body` most of the time. |
 | <span class="prop-name">disablePortal</span> | <span class="prop-type">bool</span> | <span class="prop-default">false</span> | Disable the portal behavior. The children stay within it's parent DOM hierarchy. |