title: Getting an array of column names at SheetJS
body: <p>I'm trying to parse an Excel spreadsheet (.xlsx) into JSON.</p>
  
  <p>I'm using the <a href="https://github.com/SheetJS/js-xlsx" rel="noreferrer">SheetJS</a> node package for it.</p>
  
  <p>However I can't realize such a simple thing as - how do I get a column name in the same format as it is stored internally?</p>
  
  <p>Below is my code:</p>
  
  <pre><code>function _buildColumnsArray(range) {
      // range = "A1:CA38"
      // ...
      // should return ['A', ..., 'Z', 'AA', ..., 'AZ', 'BA', ..., 'BZ', 'CA'...]
  }
  
  // --------
  
  var workbook = XLSX.readFile(fileUrl),
      sheets = workbook.Sheets,
      result = {};
  
  result.sheetNames = [];
  
  for (var i = 0; i &lt; workbook.SheetNames.length; i++) {
      var sheet = workbook.Sheets[workbook.SheetNames[i]],
          csvSheet = XLSX.utils.sheet_to_csv(sheet);
  
      // '!ref' referring to a specific range by docs
      if (sheet["!ref"]) {
          var columns = _buildColumnsArray(sheet["!ref"]),
              rows = _buildRowsArray(columns, csvSheet);
  
          // build final result
          result[workbook.SheetNames[i]] = {
              columns: columns,
              rows: rows
          };
          result.sheetNames.push(workbook.SheetNames[i]);
      }
  }
  </code></pre>
  
  <p>Here is what I'm currently trying which is not perfectly working: <a href="https://jsfiddle.net/t8hej9hu/" rel="noreferrer">https://jsfiddle.net/t8hej9hu/</a></p>