Q:

accented strings not displayed correctly in csv file in Excel

I read data from mysql database and then save it to csv file. I checked on the server side, the file is correctly saved with utf8 format.
Then the user is prompted to download the file. When I download the file on my computer (MacOSX), the file is correct with utf8. (with file command in Termninal)
When I open the csv file in Excel, accented characters are wrong.
In Excel, I have AZERTY√©a instead of AZERTYéa if I open the file with a text editor.
Here is my piece of code:
    // File creation
    var reportFile = Date.now();
    fs.closeSync(fs.openSync(__dirname + '/reports/' + reportFile + '.csv', 'w'));
    var attributes = [];
    var row = [];
    fs.appendFileSync(__dirname + '/reports/' + reportFile + '.csv', "\ufeff");

    for(var x = 0; x<fields.length; x++) attributes.push(fields[x].name);
    fs.appendFile(__dirname + '/reports/' + reportFile + '.csv', attributes.join('|'), function (err) {
        if(err) console.log('Error appending fields', err);
        fs.appendFileSync(__dirname + '/reports/' + reportFile + '.csv', '\n');
        for(var x = 0; x<results.length; x++) {
            row = [];
            for(var y = 0; y<attributes.length; y++){
                   row.push(results[x][attributes[y]]);
            }
            fs.appendFileSync(__dirname + '/reports/' + reportFile + '.csv', row.join('|'));
            fs.appendFileSync(__dirname + '/reports/' + reportFile + '.csv', '\n');
        }
        // file download
        req.reportFile = reportFile;
        res.setHeader('Content-disposition', 'attachment; filename='+__dirname + '/reports/' + reportFile + '.csv');
      res.set('Content-Type', 'text/csv; charset=utf-8');   

        fs.readFile(__dirname + '/reports/' + reportFile + '.csv', 'utf8', function (err,data) {
            if (err) {
                return console.log(err);
            }
            console.log(data);
            res.header("Access-Control-Allow-Origin", "*");
            res.status(200).send(data);         
        });
        });

A:

I finnaly found the solution. It was a BOM problem when sending the file. I tought that it was already set because I set it when writing the file....
I changed this line
    res.status(200).send(data);         

to 
    res.status(200).send('\ufeff'+data);         

