Add extracted source directory and README navigation

extracted-source/node_modules/default-browser-id/index.js

@@ -0,0 +1,18 @@
+import {promisify} from 'node:util';
+import process from 'node:process';
+import {execFile} from 'node:child_process';
+
+const execFileAsync = promisify(execFile);
+
+export default async function defaultBrowserId() {
+	if (process.platform !== 'darwin') {
+		throw new Error('macOS only');
+	}
+
+	const {stdout} = await execFileAsync('defaults', ['read', 'com.apple.LaunchServices/com.apple.launchservices.secure', 'LSHandlers']);
+
+	// `(?!-)` is to prevent matching `LSHandlerRoleAll = "-";`.
+	const match = /LSHandlerRoleAll = "(?!-)(?<id>[^"]+?)";\s+?LSHandlerURLScheme = (?:http|https);/.exec(stdout);
+
+	return match?.groups.id ?? 'com.apple.Safari';
+}