I am working on the following problem: I want to download an .xlsx file (on click) using SheetJS to create the workbook and FileSaver to save the file. The problem I encounter is, that when exceeding about 100k rows, the file cannot be written. Code snippet of how I build the whole process (mainly taken from sheetjs examples and the following tutorial https://www.youtube.com/watch?v=41rOAt-zCu4):
let wb = XLSX.utils.book_new()
wb.Props = {
Title: 'Test Sheet',
Subject: 'Test file',
Author: 'Firstname Lastname'
}
// create worksheet in new workbook, write data, use array of arrays
wb.SheetNames.push('Sheet1')
// rowData is the array of arrays bigger than 90k
let wsData = rowData
let ws = XLSX.utils.aoa_to_sheet(wsData)
wb.Sheets['Sheet1'] = ws
let wbout = XLSX.write(wb, {bookType: 'xlsx', type: 'binary'})
// until here the workbook with the test sheet is created, but not ready to be downloaded by user
// for saving, we use file-saver. it needs a different format (octet), which can be generated
// using the s2ab function
function s2ab (s) {
let buf = new ArrayBuffer(s.length)
let view = new Uint8Array(buf)
for (var i = 0; i < s.length; i++) view[i] = s.charCodeAt(i) & 0xFF
return buf
}
FileSaver.saveAs(new Blob([s2ab(wbout)], {type: 'application/octet-stream'}), 'test.xlsx')
I had the idea of writing several excel-sheets, each with 90000 rows, but I assume, that does not matter because the object I want to write simply is too big for the local memory? And I think the error is produced by the file-saver when producing the octet-format, but I am not sure.
So, I was searching for a solution and I thought of streams. Instead of generating the whole object and then trying to write it, I would like to write while generating the rows and write row by row. This should not use up my memory, right?
Yet I could not find anything on how to do it (never worked with streams before etc). The main problem is memory, since the project has to be offline and has to run on the local RAM/system).
