Reading Large Excel Files with SheetJS/js-xlsx?

Question

I am using this package: https://www.npmjs.com/package/xlsx

However I can have some very large excel files that could contain 1 million rows.

I tested with 600K rows which is about 15mb excel file and my code is already crashing on localhost.

Is there away to stream it in? I know the documentation says they don't have any sort of streaming api but it talks about buffering?

 var reader = new FileReader();
    reader.onload = evt => {
      const bstr = evt.target.result;
      const wb = XLSX.read(bstr, { type: "binary" });
      const wsname = wb.SheetNames[0];
      const ws = wb.Sheets[wsname];
      const data = XLSX.utils.sheet_to_json(ws, { header: "A", defval: "" });
      });
    };
    reader.readAsBinaryString(this.file);

Answer 1

When I had to read data from a very large excel file ( about 50 mb), I converted it to csv on the backend with Excel Interop, which takes shorter time than getting data from Excel file. Then, just get the first n number of lines via stream reader. Which will give you the required data to preview. Send this to the front-end for preview. This is what I would do.