title: npm start -- args does not work if I am using that with form another script
body: <p>I have an npm script:</p>
  
  <pre><code>"start": "webpack-dev-server --open --config webpack/webpack.config.dev.js",
  </code></pre>
  
  <p>I want to create more custom scripts and to be able to pass param to the start script</p>
  
  <pre><code>"start:xyz": "npm start -- --MYPARAM=xyz"
  "start:abc": "npm start -- --MYPARAM=abc"
  </code></pre>
  
  <p>But the thing is that if I do so the param not passing through how would you fix that?</p>