Static-Env

Create dynamic static files via environmental variables in the process.env.

Installation

$npm install static-env

Quickstart

Given a file, /public/js/helloWorld.js

const name = process.env.FIRST_NAME;
const greeting = `Hello ${name}!`;

Inside your JS, i.e. /src/controllers/content.js:

const { modifyContent } = require('static-env');

modifyContent(/public/js/helloWorld.js, { FIRST_NAME: 'Tim' }, (err, data), => {
  console.log(data);

  // const name = "Tim";
  // const greeting = `Hello ${name}!`;
}

Using process.env by default

The second argument to specify variables is optional. If omitted, process.env will be used instead.

In the shell:

# an env var in the shell
$ export FIRST_NAME=John

Inside your JS, i.e. /src/controllers/content.js:

const { modifyContent } = require('static-env');

modifyContent(/public/js/helloWorld.js, (err, data), => {
  console.log(data);

  // const name = "John";
  // const greeting = `Hello ${name}!`;
}

Usage Details

static-env exposes two functions: sendModifiedContent and modifyContent. One is coupled to expressJS as an intended replacement for res.sendFile, the other can be used with any javascript framework to replace process.env variables inside a static file.

sendModifiedContent - ExpressJS Version

sendModifiedContent can be used a replacement for res.sendFile().

In the shell:

$ export FIRST_NAME=John

/public/js/helloWorld.js - the file to be served

const name = process.env.FIRST_NAME;
const greeting = `Hello ${name}!`;

/src/controllers/sendContent.js - an expressJS controller sending the file

const express = require("express")
const { sendModifiedContent } = require('static-env');

app.get('/content', sendModifiedContent("../public/js/helloWorld.js");

Test it in the shell:

$ curl http://myContentServer.com/content

const name = 'John';
const greeting = `Hello ${name}!`;

sendModifiedContent optionally takes an object that can replace the use of process.env. Note that this argument does not merge with process.env, and is a wholesale replacement. Use Object.assign() in your Implementation if your intention is to merge the object or override a single process.env variable.

/src/controllers/sendContent.js

app.get('/content', sendModifiedContent("../public/js/helloWorld.js", { FIRST_NAME: "Tim" });

shell:

$ curl http://myContentServer.com/content

const name = 'Tim';
const greeting = `Hello ${name}!`;

modifyContent - Generic Version (non-express-specific)

This will simply replace all process.env references in a static file with a corresponding environmental variable.

/public/js/helloWorld.js - the file to be served

const name = process.env.FIRST_NAME;
const greeting = `Hello ${name}!`;

/src/controllers/content.js:

modifyContent(/public/js/helloWorld.js, (err, data), => {
  console.log(data);
  // const name = 'John';
  // const greeting = `Hello ${name}!`;
}

It optionally takes an argument that can replace the use of process.env with a custom object. Note that this argument does not merge with process.env, and is a wholesale replacement. Use Object.assign() in your Implementation if your intention is to merge the object or override a single process.env variable.

modifyContent(/public/js/helloWorld.js, { FIRST_NAME: 'Tim' }, (err, data), => {
  console.log(data);
  // const name = 'Tim';
  // const greeting = `Hello ${name}!`;
}

Miscellaneous Notes

• Destructuring ({ API_URL } = process.env) currently does not work.

• This library was originally invented to allow for hosted JS libraries (drop-in UIs google maps, stripe, or twitter widget) to avoid hardcoding external URLs for dev, staging, and prod versions.

• This can technically be used in any file, not just JS files, although it will still retain the process.env form. In the future, a more generic syntax is planned.

# TERMS_AND_CONDITIONS.txt
Valid as of process.env.CURRENT_DATE

Lorem ipsum dolor sit amet...

$ curl http://myContentServer.com/terms

Valid as of 01/01/76

Lorem ipsum dolor sit amet...

Tests

To run tests, run npm run test.

License

This project is licensed under the MIT License.