title: Issues saving and reading a variable across 2 js files
body: <p>So I'm trying to get a MagicMirror module to get data from ComEd's API, compare it to the previous reading, and overwrite the previous reading with the current reading. I'm trying to use import/export, but it doesn't work.</p>
  <pre><code>'use strict';
  
  Module.register(&quot;MMM-ComEdPrice&quot;, {
  import 'previousPrice' from &quot;~/MagicMirror/modules/MMM-ComEdPrice/previousPrice.js&quot;;
  var lastPrice = previousPrice;
  
      result: [],
      // Default module config.
      defaults: {
          url: 'https://hourlypricing.comed.com/api?type=currenthouraverage',
          fadeSpeed: 2000,
          updateInterval: 5 * 60 * 1000, // every 5 minutes
      },
  </code></pre>
  <p>At the beginning of the file, and</p>
  <pre><code>},
  export { currentPrice };
  });
  </code></pre>
  <p>At the end of it.
  The second file consists of the following:</p>
  <pre><code>import { currentPrice } from &quot;modified_MMM-ComEdPrice.js&quot;;
  var previousPrice=currentPrice;
  export { previousPrice };
  </code></pre>
  <p>Update: Have also tried using fs, but it appears that I'm not using it correctly, as every line that I have put it throws an error.</p>