How to remove old files from the build dir when webpack --watch? : <p>When my <code>webpack.config.js</code> is set to watch my source files, and the output files contain a hash, then each time the build successfully completes an entirely new set of built files exists. This quickly fills up the build dir with cruft!</p>

<p>How do I make <code>webpack</code> delete the old files on each build?</p>

<pre><code>module.exports = {
  ...
  watch: true,
  output: {
    filename: '[name]-[hash:8].js'
  }
  ...
}
</code></pre>

<hr>

<p>I recognize I could use <code>webpack-dev-server</code> to build in memory but that doesn't fit my current build process.</p>
