sheetjs/demos/extendscript/test.jsx

var thisFile = new File($.fileName);  
var basePath = thisFile.path;  

#include "shim.js";
#include "xlsx.core.min.js";

var filename = "/sheetjs.xlsx";
var infile = File(basePath+filename);
infile.open("r");
infile.encoding = "binary";
var data = infile.read();
var workbook = XLSX.read(data, {type:"binary"});
var first_sheet_name = workbook.SheetNames[0];
var first_worksheet = workbook.Sheets[first_sheet_name];
var data = XLSX.utils.sheet_to_json(first_worksheet, {header:1});
alert(data);