Writing to Excel workbook using javascript and xlsx library gives error

Sorry for the delay but I am having trouble keeping up with the flood of messages from the forum.

I did not fully debug this but the first thing I see wrong is that you are not allowing the two JavaScript files to load before proceeding with the remainder of your code. If you continue to use jQuery to load the two external libraries (versus using a module loader such as requirejs) you need to hold off running the remainder of the script till after the two libraries have fully loaded.

Try this:

var urlXLSX = "https://cdnjs.cloudflare.com/ajax/libs/xlsx/0.8.6/xlsx.core.min.js";
var urlFileSaver = "https://cdnjs.cloudflare.com/ajax/libs/FileSaver.js/1.3.3/FileSaver.js";
$.when($.getScript(urlXLSX), $.getScript(urlXLSX))
  .then(function() {
    //your code here
  });  

And, also all of your code should be wrapped in a closure to prevent your variables from potentially conflicting with QuickBase's global variables:

(function(){
  //your code here
})();