feat(Drawer): add keepMounted prop (#321)

* feat(Drawer): keepMounted prop

* chore(Drawer): fix documentation and jsdoc

* chore(Drawer): update screenshots

* fix(Drawer): revert visibility hidden on transition exit done

Author: Serge Pavlyuk

src/components/Drawer/Drawer.tsx

@@ -56,6 +56,12 @@ export interface DrawerItemProps {
 
     /** The maximum width of the resizable drawer item */
     maxResizeWidth?: number;
+
+    /**
+     * Keep child components mounted when closed, prioritized over Drawer.keepMounted property
+     * @default false
+     * */
+    keepMounted?: boolean;
 }
 
 export const DrawerItem = React.forwardRef<HTMLDivElement, DrawerItemProps>(
@@ -71,6 +77,7 @@ export const DrawerItem = React.forwardRef<HTMLDivElement, DrawerItemProps>(
             minResizeWidth,
             maxResizeWidth,
             onResize,
+            keepMounted = false,
         } = props;
 
         const itemRef = React.useRef<HTMLDivElement>(null);
@@ -95,7 +102,8 @@ export const DrawerItem = React.forwardRef<HTMLDivElement, DrawerItemProps>(
             <CSSTransition
                 in={visible}
                 timeout={TIMEOUT}
-                unmountOnExit
+                mountOnEnter={!keepMounted}
+                unmountOnExit={!keepMounted}
                 classNames={b('item-transition', {direction: cssDirection})}
                 nodeRef={itemRef}
             >
@@ -144,6 +152,12 @@ export interface DrawerProps {
 
     /** Optional flag to not use `Portal` for drawer */
     disablePortal?: boolean;
+
+    /**
+     * Keep child components mounted when closed
+     * @default false
+     * */
+    keepMounted?: boolean;
 }
 
 export const Drawer: React.FC<DrawerProps> = ({
@@ -156,6 +170,7 @@ export const Drawer: React.FC<DrawerProps> = ({
     preventScrollBody = true,
     hideVeil,
     disablePortal = true,
+    keepMounted = false,
 }) => {
     let someItemVisible = false;
     React.Children.forEach(children, (child) => {
@@ -190,8 +205,8 @@ export const Drawer: React.FC<DrawerProps> = ({
         <Transition
             in={someItemVisible}
             timeout={{enter: 0, exit: TIMEOUT}}
-            mountOnEnter
-            unmountOnExit
+            mountOnEnter={!keepMounted}
+            unmountOnExit={!keepMounted}
             nodeRef={containerRef}
         >
             {(state) => {
@@ -218,6 +233,7 @@ export const Drawer: React.FC<DrawerProps> = ({
                             ) {
                                 const childVisible = Boolean(child.props.visible);
                                 return React.cloneElement(child, {
+                                    keepMounted,
                                     ...child.props,
                                     visible: childVisible && childrenVisible,
                                 });

src/components/Drawer/README.md

@@ -76,6 +76,7 @@ The Drawer module consists of two primary components: `Drawer` and `DrawerItem`.
 | onResize       | Callback function called at the end of resizing. Can be used to save the new width.     | `(width: number) => void` |         |
 | minResizeWidth | The minimum width of the resizable drawer item                                          |         `number`          |         |
 | maxResizeWidth | The maximum width of the resizable drawer item                                          |         `number`          |         |
+| keepMounted    | Keep child components mounted when closed, prioritized over Drawer.keepMounted property |         `boolean`         | `false` |
 
 ### `Drawer` Props
 
@@ -90,6 +91,7 @@ The Drawer module consists of two primary components: `Drawer` and `DrawerItem`.
 | onEscape          | Optional callback function that is called when the escape key is pressed, if the drawer is open. |            `() => void`             |         |
 | hideVeil          | Optional flag to hide the background darkening                                                   |              `boolean`              |         |
 | disablePortal     | Optional flag to not render drawer inside `Portal`                                               |              `boolean`              | `true`  |
+| keepMounted       | Keep child components mounted when closed                                                        |              `boolean`              | `false` |
 
 ## CSS API
 

src/components/Drawer/__snapshots__/Drawer.visual.test.tsx-snapshots/DrawerStories-render-story-Showcase-dark-chromium-linux.png

@@ -16,6 +16,9 @@ export function DrawerShowcase() {
     const [direction, setDirection] = React.useState<string>('left');
     const [direction2, setDirection2] = React.useState<string>('left');
 
+    const [keepMountedGlobal, setKeepMountedGlobal] = React.useState<boolean>(false);
+    const [keepMounted1, setKeepMounted1] = React.useState<boolean>(false);
+
     const hideAll = React.useCallback(() => {
         setVisible1(false);
         setVisible2(false);
@@ -41,9 +44,32 @@ export function DrawerShowcase() {
                     <RadioButton.Option value="left">left</RadioButton.Option>
                     <RadioButton.Option value="right">right</RadioButton.Option>
                 </RadioButton>
+                <br /> Keep Mounted Drawer: &nbsp;
+                <Button
+                    view="action"
+                    size="l"
+                    onClick={() => setKeepMountedGlobal(!keepMountedGlobal)}
+                >
+                    {keepMountedGlobal ? 'On' : 'Off'}
+                </Button>
+                &nbsp;&nbsp; Keep Mounted 1: &nbsp;
+                <Button
+                    disabled={!keepMountedGlobal}
+                    view="action"
+                    size="l"
+                    onClick={() => setKeepMounted1(!keepMounted1)}
+                >
+                    {keepMounted1 ? 'On' : 'Off'}
+                </Button>
             </div>
-            <Drawer className={b('drawer')} onVeilClick={hideAll} onEscape={hideAll}>
+            <Drawer
+                className={b('drawer')}
+                onVeilClick={hideAll}
+                onEscape={hideAll}
+                keepMounted={keepMountedGlobal}
+            >
                 <DrawerItem
+                    keepMounted={keepMounted1}
                     visible={visible1}
                     id="item-1"
                     className={b('item-1')}