path-key 
Get the PATH environment variable key cross-platform
It's usually PATH, but on Windows it can be any casing like Path...
Install
$ npm install --save path-key
Usage
const pathKey = require('path-key');
const key = pathKey();
//=> 'PATH'
const PATH = process.env[key];
//=> '/usr/local/bin:/usr/bin:/bin'
API
pathKey([options])
options
env
Type: Object
Default: process.env
Use a custom environment variables object.
platform
Type: string
Default: process.platform
Get the PATH key for a specific platform.
License
MIT © Sindre Sorhus