add dynamic import load module example

Author: sambacha

README.md

@@ -47,6 +47,28 @@
 //...
 ```
 
+## `load-esm.{ts,mts}`
+
+```typescript
+import { URL } from 'url';
+
+/**
+ * This uses a dynamic import to load a module which may be ESM.
+ * CommonJS code can load ESM code via a dynamic import. Unfortunately, TypeScript
+ * will currently, unconditionally downlevel dynamic import into a require call.
+ * require calls cannot load ESM code and will result in a runtime error. To workaround
+ * this, a Function constructor is used to prevent TypeScript from changing the dynamic import.
+ * Once TypeScript provides support for keeping the dynamic import this workaround can
+ * be dropped.
+ *
+ * @param modulePath The path of the module to load.
+ * @returns A Promise that resolves to the dynamically imported module.
+ */
+export function loadEsmModule<T>(modulePath: string | URL): Promise<T> {
+  return new Function('modulePath', `return import(modulePath);`)(modulePath) as Promise<T>;
+}
+```
+
 ## Motivation
 
 Establishing the best way to support cjs and esm and how to structure project to enable that (see results.txt for more info)