Use Prettier JS (#5017)

* Adds prettier

* Run lint before tests

package.json

@@ -59,13 +59,16 @@
     "eslint-plugin-flowtype": "^2.39.1",
     "flow-bin": "0.79.1",
     "gaze": "1.1.3",
+    "husky": "^1.0.0-rc.13",
     "jasmine": "3.1.0",
     "jasmine-spec-reporter": "^4.1.0",
     "jsdoc": "^3.5.5",
     "jsdoc-babel": "^0.5.0",
+    "lint-staged": "^7.2.2",
     "mongodb-runner": "4.1.0",
     "nodemon": "1.18.4",
     "nyc": "^12.0.2",
+    "prettier": "1.14.2",
     "request-promise": "4.2.2",
     "supports-color": "^5.4.0"
   },
@@ -75,7 +78,6 @@
     "lint": "flow && eslint --cache ./",
     "build": "babel src/ -d lib/ --copy-files",
     "watch": "babel --watch src/ -d lib/ --copy-files",
-    "pretest": "npm run lint",
     "test": "cross-env MONGODB_VERSION=${MONGODB_VERSION:=3.2.6} MONGODB_STORAGE_ENGINE=mmapv1 TESTING=1 jasmine",
     "coverage": "cross-env MONGODB_VERSION=${MONGODB_VERSION:=3.2.6} MONGODB_STORAGE_ENGINE=mmapv1 TESTING=1 nyc jasmine",
     "start": "node ./bin/parse-server",
@@ -96,5 +98,18 @@
     "type": "opencollective",
     "url": "https://opencollective.com/parse-server",
     "logo": "https://opencollective.com/parse-server/logo.txt?reverse=true&variant=binary"
+  },
+  "husky": {
+    "hooks": {
+      "pre-commit": "lint-staged"
+    }
+  },
+  "lint-staged": {
+    "{src,spec}/**/*.js": [
+      "prettier --write",
+      "flow",
+      "eslint --cache ./",
+      "git add"
+    ]
   }
 }