envify

What is envify?

The envify npm package is a tool that allows you to replace environment variables in your JavaScript code with their corresponding values at build time. This is particularly useful for client-side applications where you want to inject environment-specific configurations without exposing sensitive information.

What are envify's main functionalities?

Basic Environment Variable Replacement

This feature allows you to replace environment variables in your JavaScript code with their actual values. In this example, the NODE_ENV variable is replaced with 'production' during the build process.

const envify = require('envify');
const browserify = require('browserify');

browserify('./main.js')
  .transform(envify({ NODE_ENV: 'production' }))
  .bundle()
  .pipe(process.stdout);

Using with Gulp

This feature demonstrates how to use envify with Gulp, a popular task runner. The environment variable NODE_ENV is replaced with 'production' during the build process, and the resulting bundle is saved to the './dist' directory.

const gulp = require('gulp');
const browserify = require('browserify');
const source = require('vinyl-source-stream');
const envify = require('envify/custom');

gulp.task('build', function () {
  return browserify('./main.js')
    .transform(envify({ NODE_ENV: 'production' }))
    .bundle()
    .pipe(source('bundle.js'))
    .pipe(gulp.dest('./dist'));
});

Using with Grunt

This feature shows how to use envify with Grunt, another popular task runner. The environment variable NODE_ENV is replaced with 'production' during the build process, and the resulting bundle is saved to the 'dist' directory.

module.exports = function(grunt) {
  grunt.initConfig({
    browserify: {
      dist: {
        files: {
          'dist/bundle.js': ['main.js']
        },
        options: {
          transform: [['envify', { NODE_ENV: 'production' }]]
        }
      }
    }
  });

  grunt.loadNpmTasks('grunt-browserify');
  grunt.registerTask('default', ['browserify']);
};

Other packages similar to envify

dotenv

The dotenv package loads environment variables from a .env file into process.env. Unlike envify, which replaces environment variables at build time, dotenv loads them at runtime. This makes dotenv more suitable for server-side applications or development environments.

cross-env

The cross-env package allows you to set environment variables across different platforms in a consistent manner. While envify is focused on replacing environment variables in the code at build time, cross-env is used to set environment variables in scripts, making it more suitable for cross-platform development.

README

envify

Selectively replace Node-style environment variables with plain strings. Available as a standalone CLI tool and a Browserify v2 transform.

Works best in combination with uglifyify.

Installation

If you're using the module with Browserify:

npm install envify browserify

Or, for the CLI:

sudo npm install -g envify

Usage

envify will replace your environment variable checks with ordinary strings - only the variables you use will be included, so you don't have to worry about, say, AWS_SECRET_KEY leaking through either. Take this example script:

if (process.env.NODE_ENV === "development") {
  console.log('development only')
}

After running it through envify with NODE_ENV set to production, you'll get this:

if ("production" === "development") {
  console.log('development only')
}

By running this through a good minifier (e.g. UglifyJS2), the above code would be stripped out completely.

However, if you bundled the same script with NODE_ENV set to development:

if ("development" === "development") {
  console.log('development only')
}

The if statement will evaluate to true, so the code won't be removed.

CLI Usage

With browserify:

browserify index.js -t envify > bundle.js

Or standalone:

envify index.js > bundle.js

You can also specify additional custom environment variables using browserify's subarg syntax, which is available in versions 3.25.0 and above:

browserify index.js -t [ envify --NODE_ENV development ] > bundle.js
browserify index.js -t [ envify --NODE_ENV production  ] > bundle.js

Module Usage

require('envify')

Returns a transform stream that updates based on the Node process' process.env object.

require('envify/custom')([environment])

If you want to stay away from your environment variables, you can supply your own object to use in its place:

var browserify = require('browserify')
  , envify = require('envify/custom')
  , fs = require('fs')

var b = browserify('main.js')
  , output = fs.createWriteStream('bundle.js')

b.transform(envify({
  NODE_ENV: 'development'
}))
b.bundle().pipe(output)

Purging process.env

By default, environment variables that are not defined will be left untouched. This is because in some cases, you might want to run an envify transform over your source more than once, and removing these values would make that impossible.

However, if any references to process.env are remaining after transforming your source with envify, browserify will automatically insert its shim for Node's process object, which will increase the size of your bundle. This weighs in at around 2KB, so if you're trying to be conservative with your bundle size you can "purge" these remaining variables such that any missing ones are simply replaced with undefined.

To do so through the command-line, simply use the subarg syntax and include purge after envify, e.g.:

browserify index.js -t [ envify purge --NODE_ENV development ]

Or if you're using the module API, you can pass _: "purge" into your arguments like so:

b.transform(envify({
    _: 'purge'
  , NODE_ENV: 'development'
}))

Contributors

• hughsk
• benjamn
• zag2art
• bjoerge
• andreypopp
• jupl