docs.sheetjs.com/docz/static/jquery/jquery.binarytransport.js

/*! https://www.henryalgus.com/reading-binary-files-using-jquery-ajax/ */
/**
 *
 * jquery.binarytransport.js
 *
 * @description. jQuery ajax transport for making binary data type requests.
 * @version 1.0
 * @author Henry Algus <henryalgus@gmail.com>
 *
 */

// use this transport for "binary" data type
$.ajaxTransport("+binary", function(options, originalOptions, jqXHR){
  // check for conditions and support for blob / arraybuffer response type
  if (window.FormData && ((options.dataType && (options.dataType == 'binary')) || (options.data && ((window.ArrayBuffer && options.data instanceof ArrayBuffer) || (window.Blob && options.data instanceof Blob))))) {
    return {
      // create new XMLHttpRequest
      send: function(headers, callback){
        // setup all variables
        var xhr = new XMLHttpRequest(),
          url = options.url,
          type = options.type,
          async = options.async || true,
          // blob or arraybuffer. Default is blob
          dataType = options.responseType || "blob",
          data = options.data || null,
          username = options.username || null,
          password = options.password || null;

        xhr.addEventListener('load', function(){
          var data = {};
          data[options.dataType] = xhr.response;
          // make callback and send data
          callback(xhr.status, xhr.statusText, data, xhr.getAllResponseHeaders());
        });

        xhr.open(type, url, async, username, password);

        // setup custom headers
        for (var i in headers) {
          xhr.setRequestHeader(i, headers[i]);
        }

        xhr.responseType = dataType;
        xhr.send(data);
      },
      abort: function(){
        jqXHR.abort();
      }
    };
  }
});