Integrate with ESlint.

.eslintrc.js

@@ -0,0 +1,31 @@
+module.exports = {
+  "env": {
+    "browser": true,
+    "es6": true
+  },
+  "extends": [
+    "google",
+    "plugin:react/recommended"
+  ],
+  "globals": {
+    "Atomics": "readonly",
+    "SharedArrayBuffer": "readonly"
+  },
+  "parserOptions": {
+    "ecmaFeatures": {
+      "jsx": true
+    },
+    "ecmaVersion": 2018,
+    "sourceType": "module"
+  },
+  "plugins": [
+    "react"
+  ],
+  "settings": {
+    "react": {
+      "version": "detect"
+    },
+  },
+  "rules": {
+  }
+};

demo/Demo.js

@@ -1,8 +1,9 @@
 import React from 'react';
-import { usePosition } from '../src/usePosition';
+import PropTypes from 'prop-types';
+import {usePosition} from '../src/usePosition';
 
 export const Demo = ({watch}) => {
-  const { latitude, longitude, timestamp, accuracy, error } = usePosition(watch);
+  const {latitude, longitude, timestamp, accuracy, error} = usePosition(watch);
 
   return (
     <code>
@@ -14,3 +15,7 @@ export const Demo = ({watch}) => {
     </code>
   );
 };
+
+Demo.propTypes = {
+  watch: PropTypes.bool,
+};

package.json

@@ -5,11 +5,12 @@
   "main": "dist/usePosition.min.js",
   "scripts": {
     "test": "jest --coverage",
+    "lint": "eslint src/**/*.js demo/**/*.js",
     "storybook": "start-storybook -p 6006",
     "build-storybook": "build-storybook",
     "build": "rollup -c -o dist/usePosition.min.js",
     "prepublishOnly": "yarn run build",
-    "ci": "yarn test && yarn build && yarn run build-storybook",
+    "ci": "yarn run lint && yarn test && yarn build && yarn run build-storybook",
     "predeploy": "yarn run ci && yarn run build-storybook",
     "deploy": "gh-pages -d storybook-static"
   },
@@ -41,8 +42,12 @@
     "@storybook/addons": "^5.1.9",
     "@storybook/react": "^5.1.9",
     "babel-loader": "^8.0.6",
+    "eslint": "^6.0.1",
+    "eslint-config-google": "^0.13.0",
+    "eslint-plugin-react": "^7.14.2",
     "gh-pages": "^2.0.1",
     "jest": "^24.8.0",
+    "prop-types": "^15.7.2",
     "react": "^16.8.0",
     "react-test-renderer": "^16.8.6",
     "rollup": "^1.16.3",

src/usePosition.js

@@ -36,9 +36,9 @@ export const usePosition = (watch = false) => {
     } else {
       geo.getCurrentPosition(onChange, onError, settings);
     }
-    
+
     return () => watcher && geo.clearWatch(watcher);
   }, [settings]);
 
-  return { ...position, error };
+  return {...position, error};
 };