Changing data in a Google spreadsheet - google-apps-script

Question

I am changing a few cells of data in a Google spreadsheet. I would like to write back the data into the spreadsheet. The problem i have is that the sheet has say 5 columns, when i add new data into one of the cells i would like to backup the old data in the next free cell in that row. When i do this i am not able to write back the data. This is my code.
var sheet = SpreadsheetApp.openByUrl("URL");
var d = sheet.getSheetByName('Form Responses').getDataRange().getValues();
var head = sheet.getSheetByName('Form Responses').getRange(1,1,1,sheet.getLastColumn()).getValues()[0];
d[29][2] = "A";
d[29][3] = "B";
d[29][4] = "C";
d[29][5] = "D";
sheet.getSheetByName('Form Responses').getRange(1,1,d.length,d[0].length).setValues(d);
This is the error i get. Incorrect range width, was 6 but should be 5
I have also tried modifying the the write back statement as
sheet.getSheetByName('Form Responses').getRange(29,1,1,d[29].length).setValues(d[29]);
In this case i get Cannot convert Array to Object[][].
What is the correct way to write back the data. Preferably i would like to write back data of that particular row only, instead of the whole sheet data.

Answer 1

The issue here is that you modify only one "row" in the array so that in the end it is not "symetric" anymore (ie every rows don't have the same length) and that causes the error you get.
possible solutions :
There are probably more than one good way to avoid that error, you could create a second array with new data (same height) and join the arrays before writing back to the sheet or, as in the example below, add a cell (or many cells) to every row in the array in a loop before assigning them a new value. Depending on the size of the array one could be better and/or easier than the other to implement... here is a simplified example that should work :
for(var n=0;n<d.length;n++){
d[n].push('');
Logger.log('row '+n+' = '+d[n]+'\n');// see the result
}
EDIT following comment :
OR you can write a single row if you change only one, just change the code to
sheet.getSheetByName('Form Responses').getRange(29,1,1,d[29].length).setValues([d[29]])
which is not far from what you tried but you were simply missing the pair of brackets to get a 2D array as required by setValues()