feat: re-export bootstrap helpers as ComponentWithAsProp, BsPropsWithAs

src/Button/index.tsx

@@ -4,7 +4,7 @@ import classNames from 'classnames';
 import BaseButton, { type ButtonProps as BaseButtonProps } from 'react-bootstrap/Button';
 import BaseButtonGroup, { type ButtonGroupProps as BaseButtonGroupProps } from 'react-bootstrap/ButtonGroup';
 import BaseButtonToolbar, { type ButtonToolbarProps } from 'react-bootstrap/ButtonToolbar';
-import { type BsPrefixRefForwardingComponent as ComponentWithAsProp } from 'react-bootstrap/esm/helpers';
+import type { ComponentWithAsProp } from '../utils/types/bootstrap';
 // @ts-ignore - we're not going to bother adding types for the deprecated button
 import ButtonDeprecated from './deprecated';
 

src/utils/types/bootstrap.test.tsx

@@ -0,0 +1,86 @@
+/* eslint-disable @typescript-eslint/no-unused-vars */
+import React from 'react';
+import type { BsPropsWithAs, ComponentWithAsProp } from './bootstrap';
+
+// Note: these are type-only tests. They don't actually do much at runtime; the important checks are at transpile time.
+
+describe('BsPropsWithAs', () => {
+  interface Props<As extends React.ElementType = 'table'> extends BsPropsWithAs<As> {
+    otherProp?: number;
+  }
+
+  it('defines optional bsPrefix, className, and as but no other props', () => {
+    const checkProps = <As extends React.ElementType = 'table'>(_props: Props<As>) => {};
+    // These are all valid props per the prop definition:
+    checkProps({ });
+    checkProps({ bsPrefix: 'bs' });
+    checkProps({ className: 'foo bar' });
+    checkProps({ as: 'tr' });
+    checkProps({ className: 'foo bar', as: 'button', otherProp: 15 });
+    // But these are all invalid:
+    // @ts-expect-error
+    checkProps({ newProp: 10 });
+    // @ts-expect-error
+    checkProps({ onClick: () => {} });
+    // @ts-expect-error
+    checkProps({ id: 'id' });
+    // @ts-expect-error
+    checkProps({ children: <tr /> });
+  });
+});
+
+describe('ComponentWithAsProp', () => {
+  interface MyProps extends BsPropsWithAs {
+    customProp?: string;
+  }
+  const MyComponent: ComponentWithAsProp<'div', MyProps> = (
+    React.forwardRef<HTMLDivElement, MyProps>(
+      ({ as: Inner = 'div', ...props }, ref) => <Inner {...props} ref={ref} />,
+    )
+  );
+
+  // eslint-disable-next-line react/function-component-definition
+  const CustomComponent: React.FC<{ requiredProp: string }> = () => <span />;
+
+  it('is defined to wrap a <div> by default, and accepts related props', () => {
+    // This is valid - by default it is a DIV so accepts props and ref related to DIV:
+    const divClick: React.MouseEventHandler<HTMLDivElement> = () => {};
+    const divRef: React.RefObject<HTMLDivElement> = { current: null };
+    const valid = <MyComponent ref={divRef} onClick={divClick} customProp="foo" />;
+  });
+
+  it('is defined to wrap a <div> by default, and rejects unrelated props', () => {
+    const btnRef: React.RefObject<HTMLButtonElement> = { current: null };
+    // @ts-expect-error because the ref is to a <button> ref, but this is wrapping a <div>
+    const invalidRef = <MyComponent ref={btnRef} customProp="foo" />;
+
+    const btnClick: React.MouseEventHandler<HTMLButtonElement> = () => {};
+    // @ts-expect-error because the handler is for a <button> event, but this is wrapping a <div>
+    const invalidClick = <MyComponent onClick={btnClick} />;
+  });
+
+  it('can be changed to wrap a <canvas>, and accepts related props', () => {
+    const canvasClick: React.MouseEventHandler<HTMLCanvasElement> = () => {};
+    const canvasRef: React.RefObject<HTMLCanvasElement> = { current: null };
+    const valid = <MyComponent as="canvas" ref={canvasRef} onClick={canvasClick} customProp="foo" />;
+  });
+
+  it('can be changed to wrap a <canvas>, and rejects unrelated props', () => {
+    const btnRef: React.RefObject<HTMLButtonElement> = { current: null };
+    // @ts-expect-error because the ref is to a <button> ref, but this is wrapping an <canvas>
+    const invalidRef = <MyComponent as="canvas" ref={btnRef} customProp="foo" />;
+
+    const btnClick: React.MouseEventHandler<HTMLButtonElement> = () => {};
+    // @ts-expect-error because the handler is for a <button> event, but this is wrapping an <canvas>
+    const invalidClick = <MyComponent as="canvas" onClick={btnClick} />;
+  });
+
+  it('can be changed to wrap a custom component, and accepts related props', () => {
+    const valid = <MyComponent as={CustomComponent} requiredProp="hello" />;
+  });
+
+  it('can be changed to wrap a custom component, and rejects unrelated props', () => {
+    // @ts-expect-error The onClick prop has not been declared for our custom component.
+    const valid = <MyComponent as={CustomComponent} requiredProp="hello" onClick={() => {}} />;
+  });
+});

src/utils/types/bootstrap.ts

@@ -0,0 +1,43 @@
+/**
+ * Types related to bootstrap components
+ */
+import React from 'react';
+
+import type { BsPrefixProps, BsPrefixRefForwardingComponent } from 'react-bootstrap/esm/helpers';
+
+/**
+ * Type helper for defining props of a component that wraps a bootstrap
+ * component. This type defines three props:
+ *    1. `className`: this component accepts additional CSS classes.
+ *    2. `bsPrefix`: locally change the class name prefix used for this component.
+ *    3. `as`: optionally specify which HTML element or Component is used, e.g. `"div"`
+ *
+ * This type assumes no `children` are allowed.
+ */
+export type BsPropsWithAs<As extends React.ElementType = React.ElementType> = BsPrefixProps<As>;
+
+/**
+ * This is a helper that can be used to define the type of a Paragon component
+ * that accepts an `as` prop.
+ *
+ * It:
+ *   - assumes you are using `forwardRef`, and sets the type of the `ref` prop
+ *     to match the type of the component passed in the `as` prop.
+ *   - assumes you are passing all unused props to the component, so adds any
+ *     props from the `as` component type to the props you specify as `Props`.
+ *
+ * Example;
+ * ```
+ * interface MyProps extends BsPropsWithAs {
+ *   customProp?: string;
+ * }
+ * export const MyComponent: ComponentWithAsProp<'div', MyProps> = (
+ *   React.forwardRef<HTMLDivElement, MyProps>(
+ *     ({ as: Inner = 'div', ...props }, ref) => <Inner {...props} ref={ref} />,
+ *   )
+ * );
+ * ```
+ * Note that you need to define the default (e.g. `'div'`) in three different places.
+ */
+export type ComponentWithAsProp<DefaultElementType extends React.ElementType, Props>
+  = BsPrefixRefForwardingComponent<DefaultElementType, Props>;