reading with option `cellDates: true` has wrong date values if original cell date was before 26th march 2018

if cells with date value have an date before 03/25/2018 and loading xlsx file with option cellDates: true the loaded cells in worksheet are one day earlier than original date value.

it(‘with option cellDates: true XLSX should parse date correctly’, function() { var wb = X.read( fs.readFileSync(‘./test_files-bug-report/check-date-bug.xlsx’), {cellDates: true, type: TYPE} ); var ws = wb.Sheets[‘check-date-bug’]; assert(dateToString(ws.B46.v) === ‘2018-6-5’); // work assert(dateToString(ws.B37.v) === ‘2018-3-27’); // work assert(dateToString(ws.B36.v) === ‘2018-3-26’); // work assert(dateToString(ws.B35.v) === ‘2018-3-25’); // fail: ‘2018-3-24’ assert(dateToString(ws.B34.v) === ‘2018-3-24’); // fail: ‘2018-3-23’ assert(dateToString(ws.B3.v) === ‘2015-1-1’); // fail: ‘2014-12-31’ assert(dateToString(ws.B2.v) === ‘2014-1-1’); // fail: ‘2013-12-31’ });

There is a fork with added test that currently fail: fork-branch: https://github.com/pluederitz/js-xlsx/tree/bug-date-parsing-cell-dates-true added test: https://github.com/pluederitz/js-xlsx/blob/bug-date-parsing-cell-dates-true/test.js#L384-L410 added xlsx file: https://github.com/pluederitz/js-xlsx/blob/bug-date-parsing-cell-dates-true/test_files-bug-report/check-date-bug.xlsx

to check bug run added test:

git clone https://github.com/pluederitz/js-xlsx.git checkout bug-date-parsing-cell-dates-true npm install make ctestserv open browser on http://127.0.0.1:8000

2nd suite “bug-reports” contains test “with option cellDates: true XLSX should parse date correctly (also date before 26th of march 2018)”

added bug test also fail on running tests under node.js

npm test

[Coada]

I had the same issue, and ended up parsing it on my own:

function excelDateToISODateString(excelDateNumber) {
    return new Date(Math.round((excelDateNumber - 25569) * 86400 * 1000)).toISOString().substring(0, 10);
}

This is based on a Stackoverflow answer: https://stackoverflow.com/a/22352911/11599033

[g1r0]

Workaround: use SSF library to convert raw excel number dates.

let workbook = XLSX.read(data, { type, cellDates: **false** });
const ws = workbook.Sheets[workbook.SheetNames[0]];
const dateMode = workbook.Workbook.WBProps.date1904;
let val = ws.B3.v;
XLSX.SSF.format('YYYY-MM-DD', val, { date1904: dateMode }));