preactjsGH-591: fix service worker being loaded from cdn issue

- introduced new cli args to define swPath, default would be '/'.
- decoupled from using webpack public path, better to be implicit

packages/cli/lib/index.js

@@ -36,7 +36,8 @@ prog
 	.option('--src', 'Specify source directory', 'src')
 	.option('--dest', 'Specify output directory', 'build')
 	.option('--cwd', 'A directory to use instead of $PWD', '.')
-	.option('--sw', 'Generate and attach a Service Worker', true)
+  .option('--sw', 'Generate and attach a Service Worker', true)
+  .option('--swPath', 'Specify service worker file location, default is root', '/')
 	.option('--json', 'Generate build stats for bundle analysis')
 	.option('--template', 'Path to custom HTML template')
 	.option('--preload', 'Adds preload tags to the document its assets', false)

packages/cli/lib/lib/entry.js

@@ -1,4 +1,4 @@
-/* global __webpack_public_path__ */
+/* global (process.env.SW_PATH || __webpack_public_path__) */
 
 import * as Preact from 'preact';
 const { h, render, hydrate } = Preact;
@@ -14,17 +14,17 @@ if (process.env.NODE_ENV === 'development') {
 	// only add a debug sw if webpack service worker is not requested.
 	if (process.env.ADD_SW === undefined && 'serviceWorker' in navigator) {
 		// eslint-disable-next-line no-undef
-		navigator.serviceWorker.register(__webpack_public_path__ + 'sw-debug.js');
+		navigator.serviceWorker.register((process.env.SW_PATH || __webpack_public_path__) + 'sw-debug.js');
 	} else if (process.env.ADD_SW && 'serviceWorker' in navigator) {
 		// eslint-disable-next-line no-undef
 		navigator.serviceWorker.register(
-			__webpack_public_path__ + (process.env.ES_BUILD ? 'sw-esm.js' : 'sw.js')
+			(process.env.SW_PATH || __webpack_public_path__) + (process.env.ES_BUILD ? 'sw-esm.js' : 'sw.js')
 		);
 	}
 } else if (process.env.ADD_SW && 'serviceWorker' in navigator) {
 	// eslint-disable-next-line no-undef
 	navigator.serviceWorker.register(
-		__webpack_public_path__ + (process.env.ES_BUILD ? 'sw-esm.js' : 'sw.js')
+		(process.env.SW_PATH || __webpack_public_path__) + (process.env.ES_BUILD ? 'sw-esm.js' : 'sw.js')
 	);
 }
 

packages/cli/lib/lib/webpack/webpack-client-config.js

@@ -203,7 +203,8 @@ function isProd(config) {
 				'process.env.ADD_SW': config.sw,
 				'process.env.ES_BUILD': false,
 				'process.env.ESM': config.esm,
-				'process.env.PRERENDER': config.prerender,
+        'process.env.PRERENDER': config.prerender,
+        'process.env.SW_PATH': JSON.stringify(config.swPath)
 			}),
 		],