fix: start command on Windows (#490)

package.json

@@ -4,8 +4,8 @@
   "description": "library for turn-based games",
   "repository": "https://github.com/nicolodavis/boardgame.io",
   "scripts": {
-    "start": "bash ./scripts/dev.sh",
-    "dev:client": "(cd examples/react-web; npm start)",
+    "start": "node scripts/install-web.js && npx concurrently npm:dev:server npm:dev:client",
+    "dev:client": "cd examples && cd react-web && npm start",
     "dev:server": "cross-env NODE_ENV=development nodemon -w src -w examples -e js,ts --exec babel-node --extensions '.ts,.js' --ignore 'src/**/*.test.ts' --presets @babel/preset-env examples/react-web/server.js",
     "build": "cross-env BABEL_ENV=rollup rollup --config rollup.npm.js",
     "benchmark": "babel-node --presets @babel/preset-env benchmark/index.js",

scripts/install-web.js

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2019 The boardgame.io Authors
+ *
+ * Use of this source code is governed by a MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ */
+
+const path = require('path');
+const { spawnSync } = require('child_process');
+const { existsSync } = require('fs');
+
+const projectRoot = path.resolve(__dirname, '../');
+const webExamplePath = path.resolve(projectRoot, './examples/react-web');
+const modulesPath = path.resolve(webExamplePath, './node_modules');
+
+const hasModules = existsSync(modulesPath);
+
+if (!hasModules) {
+  installDependencies();
+}
+
+console.log('Starting the application...');
+
+function installDependencies() {
+  const isWindowsOs = process.platform === 'win32';
+  const npmCommand = isWindowsOs ? 'npm.cmd' : 'npm';
+
+  console.log('Installing web dependencies...');
+
+  spawnSync(npmCommand, ['install'], {
+    cwd: webExamplePath,
+    stdio: 'inherit',
+  });
+}