title: How to create a source map for WebPack?
body: <p>My current <code>webpack.config</code> file</p>
  <pre><code>module.exports = {
      entry: &quot;./entry.js&quot;,
      output: {
          devtoolLineToLine: true,
          sourceMapFilename: &quot;./bundle.js.map&quot;,
          pathinfo: true,
          path: __dirname,
          filename: &quot;bundle.js&quot;
      },
      module: {
          loaders: [
              { test: /\.css$/, loader: &quot;style!css&quot; }
          ]
      },
  };
  </code></pre>
  <p>I was reading here <a href="https://webpack.github.io/docs/configuration.html" rel="noreferrer">https://webpack.github.io/docs/configuration.html</a> and found the following:</p>
  <p><code>output.sourceMapFilename</code></p>
  <blockquote>
  <p>[file] is replaced by the filename of the JavaScript file.</p>
  <p>[id] is replaced by the id of the chunk.</p>
  <p>[hash] is replaced by the hash of the compilation.</p>
  </blockquote>
  <p>I've added it above as you can see, but when my webpack watch runs, I don't see a map file?</p>
  <p>How is this done?</p>