title: Is it possible to consume environment variables inside of npm / package.json?
body: <p>I'm attempting to build a package.json so that when running a NodeJS app on Heroku it will run the scripts.postinstall step using an environment variable. For example:</p>
  
  <pre><code>...
  "scripts": {
    "postinstall": "command $ENV_VAR"}
  },
  ...
  </code></pre>
  
  <p>I've looked at the <a href="https://docs.npmjs.com/misc/scripts" rel="noreferrer">docs</a> and wasn't able to find something saying I can.</p>
  
  <p>Is this even possible? Is this even desirable and "I'm Doing It Wrong"™?</p>