title: npm package.json OS specific script
body: <p>I would like to create a <code>package.json</code> build script that executes slightly different set of commands when run from Windows, Linux, Mac.</p>
  
  <p>The problem is that I cannot find a way to put it in <code>package.json</code> file that will run without problems at every system.</p>
  
  <p>Here is an example that I would like to have:</p>
  
  <pre><code>"scripts" : {
      "build.windows" : "echo do windows specific stuff",
      "build.linux" : "echo do linux specific stuff",
      "build.mac" : "echo do mac specific stuff",
      "build" : "??????????????" &lt;- what to put here to execute script designed for OS
                                    on which npm is running
  }
  </code></pre>