First of all, you need to create a "config" directory in the root of your project and add a "default.json" file in it with the settings required by your app.

From server

Just import and use it, isomorphic-config will make use of server side capabilities to read the configuration file ("/config/default.json") and retrieve the configurations in it.

const isomorphicConfig = require("isomorphic-config");
const config = isomorphicConfig.server;
const express =  require("express");

let server = express();
server.listen(config.port, (err) => {
    if (err) {
        throw new Error(err);
    } else {
        console.info('Listening at http://localhost: ', config.port);
    }
});

From client

In order to use the config in a client app, you would need to expose it in a global variable ("CONFIG") from the server initial render, for later use in the app (see the "Hello" example).

server initial render (server.js)

const isomorphicConfig = require("isomorphic-config");

const express = require('express');
const server = express();
const hello = require("./Hello.js");

// You would be wise to only expose to the client non-sensitive configuration.
// It's a good idea to keep all client configurations in a "client" key and only expose that:
const clientConfig = {client: isomorphicConfig.client};
server.get('/', function (req, res) {
    res.send(
        `<!DOCTYPE html>
        <html lang="en">
           <head>
                <title>Hello Isomorphic Config</title>
                <script charSet="UTF-8">var CONFIG=${JSON.stringify(clientConfig)}</script>
           </head>
           <body>
               ${hello}
               <script>alert(CONFIG.client.greeting);</script>
           </body>
        </html>`
    );
});
server.listen(isomorphicConfig.server.port, function () {
    console.log(`Example app listening on port ${isomorphicConfig.server.port}!`);
});

Hello component (Hello.js)

const isomorphicConfig = require("isomorphic-config");
const config = isomorphicConfig.client;
const hello = `<div class="greeting">${config.greeting}</div>`
module.exports = hello;

Environment Variables

Inspired by the config module, you can define environment variables to override specific configurations. If you're running on a server, isomorphic-config will check for the existance of a given environment variable and replace the config associated to it with it's value.

To enable custom environment variables, create a configuration file, custom-environment-variables.json (and place it in the "config") directory mapping the environment variable names into your configuration structure. For example:

{
  "server": {
    "port": "PORT"
  },
  "client": {
    "greeting": "GREETING"
  }
}

...would cause isomorphic-config to check for the environment variables PORT and GREETING. If they exist, they would override the values for server.port, and client.greeting in your configuration.

Why use it?

to centralize the way configurations are requested throughout your isomorphic application. The config module works only on server side because it uses file system to read a config file. Isomorphic Config does the same but also attemps to read the configuration from a client Global variable. Also, unlike config, it only supports json format, so code is more straight-foward and has less dependencies.

Keywords

FAQs

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Package last updated on 13 Dec 2017

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Install

isomorphic-config