title: Deciding whether to save to devDependencies or dependencies?
body: <p>I'm building a react/express app and want to make sure I'm setting up my package.json so that dev packages go under <code>devDependencies</code>, and production packages go under <code>dependencies</code>. </p>
  
  <p>When downloading a new npm package, what's the quickest way to find out whether I can save it using <code>--save</code> or using <code>--save-dev</code>? For example, here is my current package.json:</p>
  
  <pre><code>  "devDependencies": {
      "babel-eslint": "^7.2.3",
      "babel-loader": "^7.1.2",
      "eslint": "^4.6.0",
      "eslint-plugin-react": "^7.3.0",
      "jest": "^20.0.4"
    },
    "dependencies": {
      "babel-cli": "^6.26.0",
      "babel-polyfill": "^6.26.0",
      "babel-preset-env": "^1.6.0",
      "babel-preset-react": "^6.24.1",
      "babel-preset-stage-2": "^6.24.1",
      "ejs": "^2.5.7",
      "express": "^4.15.4",
      "pm2": "^2.6.1",
      "react": "^15.6.1",
      "react-dom": "^15.6.1",
      "webpack": "^3.5.5"
    }
  </code></pre>
  
  <p>I had a hard time looking up which section each package should go on. I tried looking it up for each individual dependency but never got a really decisive answer so I don't know if I did so optimally.</p>
  
  <p>What's the best way when downloading an npm package to find whether I can save it using <code>--save-dev</code>?</p>