title: How can I convert an onload promise into Async/Await
body: <p>I have the following Typescript that I would like to use <code>async</code>/<code>await</code> on.  But I can't seem to sort it out in my head how to do this.</p>
  
  <pre><code>private getWorkbookFromFile2(excelFile: File): Promise&lt;xlsx.IWorkBook&gt; {
      var loadedPromise = new Promise&lt;xlsx.IWorkBook&gt;((resolve, reject) =&gt; {
          var reader = new FileReader();
  
          reader.onload = (event: any) =&gt; {
              var data = event.target.result;
  
              var workbook = xlsx.read(data, { type: 'binary' });
  
              console.log(workbook.SheetNames);
              resolve(workbook);
          };
          reader.readAsBinaryString(excelFile);
      });
  
      return loadedPromise;
  }
  </code></pre>
  
  <p>Can someone show me how this Typescript promise can be converted to use <code>async</code>/<code>await</code></p>