fix(babel/polyfill): update logic

vue-cli@3.0.0-beta11 changed from .babelrc to babel.config.js

fixes #12

Author: johnleider

generator/helpers.js

@@ -5,12 +5,11 @@ module.exports = function (api) {
     updateBabelConfig (callback) {
       let config, configPath
 
-      const rcPath = api.resolve('./.babelrc')
+      const rcPath = api.resolve('./babel.config.js')
       const pkgPath = api.resolve('./package.json')
       if (fs.existsSync(rcPath)) {
         configPath = rcPath
-        config = JSON.parse(fs.readFileSync(rcPath, { encoding: 'utf8' }))
-        config = callback(config)
+        config = callback(require(rcPath))
       } else if (fs.existsSync(pkgPath)) {
         configPath = pkgPath
         config = JSON.parse(fs.readFileSync(pkgPath, { encoding: 'utf8' }))
@@ -23,9 +22,11 @@ module.exports = function (api) {
       }
 
       if (configPath) {
+        const moduleExports = configPath !== pkgPath ? 'module.exports = ' : ''
+
         fs.writeFileSync(
           configPath,
-          JSON.stringify(config, null, 2),
+          `${moduleExports}${JSON.stringify(config, null, 2)}`,
           { encoding: 'utf8' }
         )
       } else {

generator/index.js

@@ -56,12 +56,12 @@ module.exports = (api, opts, rootOpts) => {
     // Add polyfill
     if (opts.usePolyfill) {
       helpers.updateBabelConfig(cfg => {
-        if (!cfg.presets) return
+        if (!cfg.presets) return cfg
 
         const vuePresetIndex = cfg.presets.findIndex(p => Array.isArray(p) ? p[0] === '@vue/app' : p === '@vue/app')
         const isArray = Array.isArray(cfg.presets[vuePresetIndex])
 
-        if (vuePresetIndex < 0) return
+        if (vuePresetIndex < 0) return cfg
 
         if (isArray) {
           cfg.presets[vuePresetIndex][1]['useBuiltIns'] = 'entry'