Add flow and babel with eslint

Author: vukanac

.babelrc

@@ -1,3 +1,4 @@
 {
-  "presets": ["flow"]
+  "presets": ["flow"],
+  "retainLines": true
 }

.eslintrc.js

@@ -1,3 +1,10 @@
 module.exports = {
-    "extends": "airbnb"
-};
+  "extends": [
+    "airbnb",
+    "plugin:flowtype/recommended"
+  ],
+  "parser": "babel-eslint",
+  "plugins": [
+    "flowtype"
+  ]
+};

.flowconfig

@@ -5,6 +5,10 @@
 [libs]
 
 [lints]
+# all=off by default
+all=warn
+untyped-type-import=error
+sketchy-null-bool=off
 
 [options]
 

package-lock.json

@@ -5,6 +5,10 @@
   "main": "dist/index.js",
   "scripts": {
     "flow": "flow",
+    "flow start": "flow start",
+    "flow stop": "flow stop",
+    "flow status": "flow status",
+    "flow coverage": "flow coverage",
     "test": "mocha --recursive --timeout=10000",
     "build": "babel src/ -d dist/",
     "prepublish": "npm run build"
@@ -26,10 +30,12 @@
   "homepage": "https://github.com/vukanac/ci-base-nodejs#readme",
   "devDependencies": {
     "babel-cli": "^6.26.0",
+    "babel-eslint": "^8.0.3",
     "babel-preset-flow": "^6.23.0",
     "chai": "^4.1.2",
     "eslint": "^4.13.1",
     "eslint-config-airbnb": "^16.1.0",
+    "eslint-plugin-flowtype": "^2.40.1",
     "eslint-plugin-import": "^2.8.0",
     "eslint-plugin-jsx-a11y": "^6.0.2",
     "eslint-plugin-react": "^7.5.1",

package.json

@@ -1,4 +1,16 @@
-type Person = {
-  name: string,
-  age: number
-};
+/* @flow */
+
+function foo(x: ?number): string {
+  if (x) {
+    return `${x}`;
+  }
+  return 'default string';
+}
+
+// type Person = {
+//   name: string,
+//   age: number
+// };
+
+
+foo(1);