Interactivity API: Create @wordpress/interactivity-router module

packages/dependency-extraction-webpack-plugin/lib/util.js

@@ -59,9 +59,11 @@ function defaultRequestToExternal( request ) {
 /**
  * Default request to external module transformation
  *
- * Currently only @wordpress/interactivity
+ * Currently only @wordpress/interactivity and `@wordpress/interactivity-router`
+ * are supported.
  *
- * Do not use the boolean shorthand here, it's only handled for the `requestToExternalModule` option.
+ * Do not use the boolean shorthand here, it's only handled for the
+ * `requestToExternalModule` option.
  *
  * @param {string} request Module request (the module name in `import from`) to be transformed
  * @return {string|Error|undefined} The resulting external definition.
@@ -71,13 +73,19 @@ function defaultRequestToExternal( request ) {
  */
 function defaultRequestToExternalModule( request ) {
 	if ( request === '@wordpress/interactivity' ) {
-		// This is a special case. Interactivity does not support dynamic imports at this
-		// time. We add the external "module" type to indicate that webpack should
-		// externalize this as a module (instead of our default `import()` external type)
-		// which forces @wordpress/interactivity imports to be hoisted to static imports.
+		// This is a special case. Interactivity does not support dynamic imports at
+		// this time. We add the external "module" type to indicate that webpack
+		// should externalize this as a module (instead of our default `import()`
+		// external type) which forces @wordpress/interactivity imports to be
+		// hoisted to static imports.
 		return `module ${ request }`;
 	}
 
+	if ( request === '@wordpress/interactivity-router' ) {
+		// Assumes this is usually giong to be used as a dynamic import.
+		return `import ${ request }`;
+	}
+
 	const isWordPressScript = Boolean( defaultRequestToExternal( request ) );
 
 	if ( isWordPressScript ) {

packages/scripts/config/webpack.config.js

@@ -415,6 +415,8 @@ if ( hasExperimentalModulesFlag ) {
 			},
 		},
 
+		externalsType: 'module',
+
 		plugins: [
 			new webpack.DefinePlugin( {
 				// Inject the `SCRIPT_DEBUG` global, used for development features flagging.