WebAssembly bindings for the XLNT library
https://www.npmjs.com/package/xlnt
I'm writing a series of posts in my blog about porting C++ to WASM.
You can take a look here: Excel-ent experiment with WebAssembly
<script src="./xlnt.js"></script>
<script>
    load_xlnt().then(function(xlnt)
    {
        book = new xlnt.workbook();
        sheet = book.active_sheet();
        sheet.using_cell("B2", c => c.set_value("asd"));
        book.download("demo.xlsx");
        
        sheet.delete();
        book.delete();
    });
</script>