What is the purpose for the fallback option in ExtractTextPlugin.extract : <p>Using the example from <a href="https://github.com/webpack-contrib/extract-text-webpack-plugin" rel="noreferrer">webpack-contrib/extract-text-webpack-plugin</a>:</p>

<pre><code>const ExtractTextPlugin = require('extract-text-webpack-plugin');

module.exports = {
  module: {
    rules: [
      {
        test: /\.scss$/,
        use: ExtractTextPlugin.extract({
          fallback: 'style-loader',
          //resolve-url-loader may be chained before sass-loader if necessary
          use: ['css-loader', 'sass-loader']
        })
      }
    ]
  },
  plugins: [
    new ExtractTextPlugin('style.css')
    //if you want to pass in options, you can do so:
    //new ExtractTextPlugin({
    //  filename: 'style.css'
    //})
  ]
}
</code></pre>

<p>What is the purpose of the fallback option?</p>

<p>How I see this snippet to work is: </p>

<p>I instruct webpack to use the <code>ExtractTextPlugin</code> on every <code>.scss</code> file it encounter. I am telling <code>ExtractTextPlugin</code> to use <code>['css-loader', 'sass-loader']</code> loaders to generate the css. Webpack will then emit extra <code>style.css</code> file containing the css.</p>

<p>I can then reference this file in my index.html or if I am using html-webpack-plugin it will be added automatically to it.</p>

<p>I can remove the <code>fallback: 'style-loader',</code> option and everything continues to work.</p>

<p>What does it mean to fallback to <code>style-loader</code>?</p>

<p>How/When the fallback gets triggered?</p>

<p>I understand what <code>style-loader</code> is doing and how it is modifying the DOM with style tag if I am not using the <code>ExtractTextPlugin</code>. I just can't understand the fallback option when I am using <code>ExtractTextPlugin</code>.</p>
