install and run prettier

package-lock.json

@@ -3257,6 +3257,12 @@
       "integrity": "sha1-IZMqVJ9eUv/ZqCf1cOBL5iqX2lQ=",
       "dev": true
     },
+    "prettier": {
+      "version": "1.18.2",
+      "resolved": "https://registry.npmjs.org/prettier/-/prettier-1.18.2.tgz",
+      "integrity": "sha512-OeHeMc0JhFE9idD4ZdtNibzY0+TPHSpSSb9h8FqtP+YnoZZ1sl8Vc9b1sasjfymH3SonAF4QcA2+mzHPhMvIiw==",
+      "dev": true
+    },
     "private": {
       "version": "0.1.8",
       "resolved": "https://registry.npmjs.org/private/-/private-0.1.8.tgz",

package.json

@@ -5,12 +5,14 @@
   "license": "GPLv3",
   "scripts": {
     "build": "babel src --out-dir dist",
-    "lint": "eslint --ignore-path .gitignore ."
+    "lint": "eslint --ignore-path .gitignore .",
+    "format": "prettier --ignore-path .gitignore --write \"**/*.+(js|json)\""
   },
   "devDependencies": {
     "@babel/cli": "^7.5.5",
     "@babel/core": "^7.5.5",
     "@babel/preset-env": "^7.5.5",
-    "eslint": "^6.1.0"
+    "eslint": "^6.1.0",
+    "prettier": "^1.18.2"
   }
 }

src/example.js

@@ -1,10 +1,10 @@
-const username = 'freddy'
-typeof username === 'string'
+const username = "freddy";
+typeof username === "string";
 
-if (!('serviceWorker' in navigator)) {
+if (!("serviceWorker" in navigator)) {
   // you have an old browser :-(
 }
 
-const greeting = 'hello'
-console.log(`${greeting} world!`)
-;[1, 2, 3].forEach(x => console.log(x))
+const greeting = "hello";
+console.log(`${greeting} world!`);
+[1, 2, 3].forEach(x => console.log(x));