Rename .babelrc and .postcssrc.yml to babel.config.js postcss.config.js

.babelrc

@@ -1,26 +0,0 @@
-{
-  "presets": [
-    [
-      "@babel/preset-env",
-      {
-        "modules": false,
-        "targets": {
-          "browsers": "> 1%",
-          "uglify": true
-        },
-        "useBuiltIns": true
-      }
-    ],
-    "@babel/preset-flow"
-  ],
-  "plugins": [
-    "@babel/plugin-syntax-dynamic-import",
-    "@babel/plugin-proposal-object-rest-spread",
-    [
-      "@babel/plugin-proposal-class-properties",
-      {
-        "spec": true
-      }
-    ]
-  ]
-}

.postcssrc.yml

@@ -1,3 +0,0 @@
-plugins:
-  postcss-import: {}
-  postcss-cssnext: {}

babel.config.js

@@ -0,0 +1,72 @@
+module.exports = function(api) {
+  var validEnv = ['development', 'test', 'production']
+  var currentEnv = api.env()
+  var isDevelopmentEnv = api.env('development')
+  var isProductionEnv = api.env('production')
+  var isTestEnv = api.env('test')
+
+  if (!validEnv.includes(currentEnv)) {
+    throw new Error(
+      'Please specify a valid `NODE_ENV` or ' +
+        '`BABEL_ENV` environment variables. Valid values are "development", ' +
+        '"test", and "production". Instead, received: ' +
+        JSON.stringify(currentEnv) +
+        '.'
+    )
+  }
+
+  return {
+    presets: [
+      isTestEnv && [
+        '@babel/preset-env',
+        {
+          targets: {
+            node: 'current'
+          }
+        }
+      ],
+      (isProductionEnv || isDevelopmentEnv) && [
+        '@babel/preset-env',
+        {
+          forceAllTransforms: true,
+          useBuiltIns: 'entry',
+          corejs: 3,
+          modules: false,
+          exclude: ['transform-typeof-symbol']
+        }
+      ]
+    ].filter(Boolean),
+    plugins: [
+      'babel-plugin-macros',
+      '@babel/plugin-syntax-dynamic-import',
+      isTestEnv && 'babel-plugin-dynamic-import-node',
+      '@babel/plugin-transform-destructuring',
+      [
+        '@babel/plugin-proposal-class-properties',
+        {
+          loose: true
+        }
+      ],
+      [
+        '@babel/plugin-proposal-object-rest-spread',
+        {
+          useBuiltIns: true
+        }
+      ],
+      [
+        '@babel/plugin-transform-runtime',
+        {
+          helpers: false,
+          regenerator: true,
+          corejs: false
+        }
+      ],
+      [
+        '@babel/plugin-transform-regenerator',
+        {
+          async: false
+        }
+      ]
+    ].filter(Boolean)
+  }
+}

postcss.config.js

@@ -0,0 +1,12 @@
+module.exports = {
+  plugins: [
+    require('postcss-import'),
+    require('postcss-flexbugs-fixes'),
+    require('postcss-preset-env')({
+      autoprefixer: {
+        flexbox: 'no-2009'
+      },
+      stage: 3
+    })
+  ]
+}