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Load your environment configuration in a easy way and call in your code only one time and will be available through "process.env".

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It's possible to reload the environment configuration by change the config file. Attention, process.env convert all values to string, must cast in case isn't a string, ex:

port number for your web server => 3000

console.log(process.env.WEB_PORT);// is going be '3000'
console.log(Number(process.env.WEB_PORT));// is going be 3000

a JSON object with some options => {port: 4000, address: 'localhost'}

// is gonna be '{"port":4000,"address":"localhost"}'
// internally we are using JSON.stringify

// is gonna be { port: 4000, address: 'localhost' }

If wants to get the primitive value of the specified object can use process.loadenv.'key' and don't need to do any conversion.

 typeof process.loadenv.MONGODB_URL === 'string'
 typeof process.loadenv.APP_PORT === 'number'
 isJSON(process.loadenv.WINDOW_SIZE, true)


var load = require('load-env') or require('load-env')()

load([environment], [config_path], [reload*])

*reload accepts a bool (default to false/null), if wants to reload the enviroment when the configuration file is updated then pass true.

from CLI: node my_app --env heroku

in your app just need to make the require and call load();

--env is mandatory in CLI

config folder must be in your application current directory or can use [path] to define the localization of your config files, and the files must have the exactly name as your environment (heroku.json will be env heroku).



JSON strutucture for config file

{"var_name": {"format": "", "value":""}}

format: value with placeholders
    %s - String
    %d - Number (both integer and float)
    %j - JSON
value: object with the values to replace the placeholders


      "MONGODB_URL": {
        "format": "mongodb://%s:%s@%s/%s?%s",
        "value" : {
          "user": "xpto",
          "pwd": "password",
          "host": "",
          "db": "lilidb",
          "extra": "numberOfRetries=10&retryMiliSeconds=10000"
      "APP_PORT": {
        "format": "%d",
        "value" : {
          "port": 4000

   // now in your code

   require('load-env')(); // var load = require('load-env'); load();

   console.log(process.env.MONGODB_URL); // 'conn_str'
   console.log(process.env.APP_PORT); // '4000'
   console.log(process.loadenv.MONGODB_URL); // 'conn_str'
   console.log(process.loadenv.APP_PORT); // 4000
   // CLI
   node my_app --env heroku

Example with JSON objects in the configuration

    "format": "%j",
    "value": {
      "sizes": {
        "width": 1000,
        "height": 600,
        "min-width": 800,
        "min-height": 600

// we are using %j to specify is a JSON

call process.loadenv.WINDOW_SIZE will return the the JSON already parsed

{ width: 1000, height: 600, 'min-width': 800, 'min-height': 600 }

call process.env.WINDOW_SIZE must use the JSON.parse