Add future date in Google script and Goggle Sheet - date

Question

I use Google sheet and Cryptofinance.ai to retreive cryptocurrency prices. I have one script that works well : it appends data periodically from one row in tab A to save them in a tab B so I can make graphs and charts.
Now I'd like to add date + 1 year in the next row. Idealy, each time the script is triggered, it make two new rows : The one with the data as it is now and the one with the date + 1 year.
If you curious and want to know why I want to do that is is to make projection price using this
formula in another tab : =TREND(filter(B2:B,B2:B<>""),filter(A2:A,B2:B<>""),filter(A2:A,(N(B2:B)=0)*(A2:A>0)))
Here is my script now:
// [START modifiable parameters]
var rangeToLog = 'Portefeuille!A28:L28';
var sheetToLogTo = 'Archive BTC/USD KRAKEN';
// [END modifiable parameters]
////////////////////////////////
/**
* Appends a range of values to the end of an archive sheet.
* A timestamp is inserted in column A of each row on the archive sheet.
* All values in rangeToLog go to one row on the archive sheet.
*
* #OnlyCurrentDoc
*/
function appendValuesToArchiveBTCUSDKRAKENSheet() {
// version 1.4, written by --Hyde, 30 January 2020
// - use Array.prototype.some() to skip empty rows when concating
// - see https://support.google.com/docs/thread/27095918?msgid=27148911
// version 1.3, written by --Hyde, 26 January 2020
// - see https://support.google.com/docs/thread/26760916
var ss = SpreadsheetApp.getActive();
var valuesToLog = ss.getRange(rangeToLog).getValues();
var logSheet = ss.getSheetByName(sheetToLogTo);
if (!logSheet) {
logSheet = ss.insertSheet(sheetToLogTo);
logSheet.appendRow(['Date time', 'Data']);
}
var rowToAppend = [new Date()].concat(
valuesToLog.reduce(function concatArrays_(left, right) {
var arrayContainsData = right.some(function isNonBlanky_(element, index, array) {
return element !== null && element !== undefined && element !== '';
});
return arrayContainsData ? left.concat(right) : left;
})
);
logSheet.appendRow(rowToAppend);
}
NOW :
What I want to do:

Answer 1

The easy fix is to simply add another appendRow() call at the end of your function with the one year from now value.
function appendValuesToArchiveBTCUSDKRAKENSheet() {
// ...
logSheet.appendRow(rowToAppend);
logSheet.appendRow([new Date(new Date().setFullYear(new Date().getFullYear() + 1))]);
}
A more complex solution, but with better execution time, would have you print both rows in a single setValues() call. This follows the best practice of using batch operations, but I suspect that the easier solution above is adequate for your purpose. I do encourage you, however, to try implementing the batch operation if you want to improve your apps script skills.

Answer 2

Finally, after some research I came to this :
function expCalc(){
delLastNRows();
appendValuesToArchiveBTCUSDKRAKENSheet();
}
function delLastNRows(n){
var n=n || 1;//allows you to delete last three rows without passing function a parameter.
var ss=SpreadsheetApp.getActive();
var sh=ss.getSheetByName('Archive BTC/USD KRAKEN');
var lr=sh.getLastRow();
if(lr>=n){
for(var i=0;i<n;i++){
sh.deleteRow(sh.getLastRow());
}
}
}
// [START modifiable parameters]
var rangeToLog = 'Portefeuille!A28:L28';
var sheetToLogTo = 'Archive BTC/USD KRAKEN';
// [END modifiable parameters]
////////////////////////////////
/**
* Appends a range of values to the end of an archive sheet.
* A timestamp is inserted in column A of each row on the archive sheet.
* All values in rangeToLog go to one row on the archive sheet.
*
* #OnlyCurrentDoc
*/
function appendValuesToArchiveBTCUSDKRAKENSheet() {
// version 1.4, written by --Hyde, 30 January 2020
// - use Array.prototype.some() to skip empty rows when concating
// - see https://support.google.com/docs/thread/27095918?msgid=27148911
// version 1.3, written by --Hyde, 26 January 2020
// - see https://support.google.com/docs/thread/26760916
var ss = SpreadsheetApp.getActive();
var valuesToLog = ss.getRange(rangeToLog).getValues();
var logSheet = ss.getSheetByName(sheetToLogTo);
var sheet = ss.getSheets()[0]
if (!logSheet) {
logSheet = ss.insertSheet(sheetToLogTo);
logSheet.appendRow(['Date time', 'Data']);
}
var rowToAppend = [new Date()].concat(
valuesToLog.reduce(function concatArrays_(left, right) {
var arrayContainsData = right.some(function isNonBlanky_(element, index, array) {
return element !== null && element !== undefined && element !== '';
});
return arrayContainsData ? left.concat(right) : left;
})
);
logSheet.appendRow(rowToAppend);
logSheet.appendRow([new Date(new Date().setFullYear(new Date().getFullYear() + 1))]);
}
Works like a charm !