Salut,
Trouvé cela sur Stack :
function sheetToCsv()
{
var ssID = SpreadsheetApp.getActiveSpreadsheet().getId();
var sheet_Name = "[Your sheet name goes here]";
var requestData = {"method": "GET", "headers":{"Authorization":"Bearer "+ScriptApp.getOAuthToken()}};
var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(sheet_Name);
var sheetNameId = sheet.getSheetId().toString();
params= ssID+"/export?gid="+sheetNameId +"&format=csv";
var url = "https://docs.google.com/spreadsheets/d/"+ params;
var result = UrlFetchApp.fetch(url, requestData);
var resource = {
title: sheet_Name+".csv",
mimeType: "MimeType.CSV",
parents:[{
"id": "[Your Shared Drive Folder ID goes here]"
}]
}
var optionalArgs={supportsAllDrives: true};
var fileJson = Drive.Files.insert(resource, result, optionalArgs);
}