feat(ui-alerts): expand Alert's liveRegion to accept direct DOM element

INSTUI-4454

Author: ToMESSKa

packages/ui-alerts/src/Alert/__tests__/Alert.test.tsx

@@ -148,6 +148,24 @@ describe('<Alert />', () => {
     expect(liveRegion).toHaveAttribute('aria-live', 'polite')
   })
 
+  it('should accept a direct DOM element as liveRegion', async () => {
+    const liveRegion = document.getElementById('_alertLiveRegion')!
+    render(
+      <Alert
+        variant="success"
+        transition="none"
+        liveRegion={liveRegion}
+        liveRegionPoliteness="polite"
+        isLiveRegionAtomic
+      >
+        Success: Sample alert text.
+      </Alert>
+    )
+
+    expect(liveRegion).toHaveTextContent('Success: Sample alert text.')
+    expect(liveRegion).toHaveAttribute('aria-atomic', 'true')
+  })
+
   it('should render an icon when provided as the `renderIcon` prop', () => {
     const { container } = render(<Alert renderCustomIcon={<IconGroupLine />} />)
     const icon = container.querySelector('svg[class$="-svgIcon"]')

packages/ui-alerts/src/Alert/index.tsx

@@ -136,15 +136,15 @@ class Alert extends Component<AlertProps, AlertState> {
   }
 
   // duck type for a dom node
-  isDOMNode(n: Element | null) {
+  isDOMNode(n: Element | null | undefined) {
     return n && typeof n === 'object' && n.nodeType === 1
   }
 
   getLiveRegion() {
-    let lr = null
-    if (typeof this.props.liveRegion === 'function') {
-      lr = this.props.liveRegion()
-    }
+    const lr =
+      typeof this.props.liveRegion === 'function'
+        ? this.props.liveRegion()
+        : this.props.liveRegion
 
     return this.isDOMNode(lr) ? lr : null
   }

packages/ui-alerts/src/Alert/props.ts

@@ -51,9 +51,9 @@ type AlertOwnProps = {
    */
   variantScreenReaderLabel?: string
   /**
-   * Function that returns the DIV where screenreader alerts will be placed.
+   * A DOM element or function that returns an element where screenreader alerts will be placed.
    */
-  liveRegion?: () => Element
+  liveRegion?: Element | null | (() => Element | null | undefined)
   /**
    * Choose the politeness level of screenreader alerts, sets the value of
    * `aria-live`.
@@ -132,7 +132,7 @@ const propTypes: PropValidators<PropKeys> = {
   children: PropTypes.node,
   variant: PropTypes.oneOf(['info', 'success', 'warning', 'error']),
   margin: PropTypes.string,
-  liveRegion: PropTypes.func,
+  liveRegion: PropTypes.oneOfType([PropTypes.func, PropTypes.element]),
   liveRegionPoliteness: PropTypes.oneOf(['polite', 'assertive']),
   isLiveRegionAtomic: PropTypes.bool,
   screenReaderOnly: PropTypes.bool,