feat(drawer): add innerRef prop (#758)

packages/drawer/README.md

@@ -419,6 +419,7 @@ modal | Boolean | Indicates that the drawer is of type modal.
 dismissible | Boolean | Indicates that the drawer is of type dismissible.
 tag | String | Customizes the drawer tag type (default to `<aside>`).
 open | boolean | If true, opens drawer. If false, closes drawer.
+innerRef | RefObject | Root drawer element ref.
 
 ## Sass Mixins
 

packages/drawer/index.tsx

@@ -39,6 +39,8 @@ import {FocusTrap} from 'focus-trap';
 
 const {cssClasses: listCssClasses} = MDCListFoundation;
 
+type RefCallback<T> = (node: T) => void;
+
 export interface DrawerProps extends React.HTMLProps<HTMLElement>{
   className?: string;
   open?: boolean;
@@ -47,12 +49,17 @@ export interface DrawerProps extends React.HTMLProps<HTMLElement>{
   tag?: string;
   dismissible?: boolean;
   modal?: boolean;
+  innerRef?: RefCallback<HTMLElement> | React.RefObject<HTMLElement>;
 };
 
 interface DrawerState {
   classList: Set<string>;
 };
 
+const isRefObject = function(ref: DrawerProps['innerRef']): ref is React.RefObject<HTMLElement> {
+  return typeof ref !== 'function';
+};
+
 class Drawer extends React.Component<DrawerProps, DrawerState> {
   previousFocus: HTMLElement | null = null;
   foundation: MDCDismissibleDrawerFoundation | MDCModalDrawerFoundation;
@@ -193,6 +200,25 @@ class Drawer extends React.Component<DrawerProps, DrawerState> {
     this.foundation.handleTransitionEnd(evt);
   };
 
+  attachRef = (node: HTMLElement) => {
+    const {innerRef} = this.props;
+
+    // https://github.com/facebook/react/issues/13029#issuecomment-410002316
+    // @ts-ignore this is acceptable according to the comment above
+    this.drawerElement.current = node;
+
+    if (!innerRef) {
+      return;
+    }
+
+    if (isRefObject(innerRef)) {
+      // @ts-ignore same as above
+      innerRef.current = node;
+    } else {
+      innerRef(node);
+    }
+  }
+
   render() {
     const {
       /* eslint-disable no-unused-vars */
@@ -203,6 +229,7 @@ class Drawer extends React.Component<DrawerProps, DrawerState> {
       dismissible,
       children,
       className,
+      innerRef,
       /* eslint-enable no-unused-vars */
       tag: Tag,
       modal,
@@ -215,7 +242,7 @@ class Drawer extends React.Component<DrawerProps, DrawerState> {
           // @ts-ignore */}
         <Tag
           className={this.classes}
-          ref={this.drawerElement}
+          ref={this.attachRef}
           onKeyDown={this.handleKeyDown}
           onTransitionEnd={this.handleTransitionEnd}
           {...otherProps}

test/unit/drawer/index.test.tsx

@@ -283,3 +283,17 @@ test('click on scrim calls #foundation.handleScrimClick', () => {
   scrim.simulate('click');
   td.verify(wrapper.instance().foundation.handleScrimClick(), {times: 1});
 });
+
+test('handles object refs correctly', () => {
+  const myRef = React.createRef<HTMLElement>();
+  const wrapper = mount<Drawer>(<Drawer innerRef={myRef} />);
+  assert.isNotNull(myRef.current);
+  assert.isNotNull(wrapper.instance().drawerElement.current);
+});
+
+test('it handles function refs correctly', () => {
+  const refFn = coerceForTesting<(node: HTMLElement) => void>(td.func());
+  const wrapper = mount<Drawer>(<Drawer innerRef={refFn} />);
+  assert.isNotNull(wrapper.instance().drawerElement.current);
+  td.verify(refFn(wrapper.instance().drawerElement.current!), {times: 1});
+});