Use environment variables

.env.example

@@ -0,0 +1 @@
+PORT=3000

.gitignore

@@ -3,3 +3,7 @@ node_modules
 
 # package-lock.json (use yarn.lock instead)
 package-lock.json
+
+# Environment varibales
+.env*
+!.env*.example

package.json

@@ -9,14 +9,16 @@
     "node": ">=12.0.0"
   },
   "scripts": {
-    "start": "node src/index.js",
-    "dev": "nodemon src/index.js",
+    "start": "cross-env NODE_ENV=production node src/index.js",
+    "dev": "cross-env NODE_ENV=development nodemon src/index.js",
     "lint": "eslint .",
     "lint:fix": "eslint . --fix",
     "prettier": "prettier --check **/*.js",
     "prettier:fix": "prettier --write **/*.js"
   },
   "dependencies": {
+    "cross-env": "^6.0.3",
+    "dotenv": "^8.2.0",
     "express": "^4.17.1"
   },
   "devDependencies": {

src/config/config.js

@@ -0,0 +1,11 @@
+const dotenv = require('dotenv');
+const path = require('path');
+
+dotenv.config({
+  path: path.join(__dirname, '../../.env'),
+});
+
+module.exports = {
+  env: process.env.NODE_ENV,
+  port: process.env.PORT,
+};

src/index.js

@@ -1,6 +1,6 @@
 const app = require('./app');
+const { port } = require('./config/config');
 
-const port = 3000;
 app.listen(port, () => {
   console.log(`Listening to port ${port}`);
 });

yarn.lock

@@ -612,6 +612,13 @@ create-error-class@^3.0.0:
   dependencies:
     capture-stack-trace "^1.0.0"
 
+cross-env@^6.0.3:
+  version "6.0.3"
+  resolved "https://registry.yarnpkg.com/cross-env/-/cross-env-6.0.3.tgz#4256b71e49b3a40637a0ce70768a6ef5c72ae941"
+  integrity sha512-+KqxF6LCvfhWvADcDPqo64yVIB31gv/jQulX2NGzKS/g3GEVz6/pt4wjHFtFWsHMddebWD/sDthJemzM4MaAag==
+  dependencies:
+    cross-spawn "^7.0.0"
+
 cross-spawn@^5.0.1:
   version "5.1.0"
   resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-5.1.0.tgz#e8bd0efee58fcff6f8f94510a0a554bbfa235449"
@@ -784,6 +791,11 @@ dot-prop@^4.1.0:
   dependencies:
     is-obj "^1.0.0"
 
+dotenv@^8.2.0:
+  version "8.2.0"
+  resolved "https://registry.yarnpkg.com/dotenv/-/dotenv-8.2.0.tgz#97e619259ada750eea3e4ea3e26bceea5424b16a"
+  integrity sha512-8sJ78ElpbDJBHNeBzUbUVLsqKdccaa/BXF1uPTw3GrvQTBgrQrtObr2mUrE38vzYd8cEv+m/JBfDLioYcfXoaw==
+
 duplexer3@^0.1.4:
   version "0.1.4"
   resolved "https://registry.yarnpkg.com/duplexer3/-/duplexer3-0.1.4.tgz#ee01dd1cac0ed3cbc7fdbea37dc0a8f1ce002ce2"