getValue for the previous non empty cell in a column based on getRow value?

Question

I'm trying to write an onEdit script where I modify values on rows in Column C, and have corresponding rows in Column D & E updated with the last non empty values from Columns A & B, see screenshot:

I'm mainly having problems trying to figure the last non empty value, I feel like some sort of reverse FOR that counts backwards from the activeCell() value and checks for IFBLANK until a non blank value is found? See the script is prepared:

function onEdit() {
  var s = SpreadsheetApp.getActiveSpreadsheet();
  var r = s.getActiveCell();
  var sh = s.getActiveSheet();

  if( r.getColumn() == 3 ) {

    var activerow = r.getRow();
    var lasttime = ???
    var lastitem = ???

    s.getRange('G' + activerow.toString()).setValue(lasttime);
    s.getRange('H' + activerow.toString()).setValue(lastitem);
  }
}

Answer 1

The following piece of code does what you want.

Code

function onEdit(e) {
  if(e.range.columnStart === 3) {
    e.range.offset(0,1).setValue(getLastValue("A:A", e));
    e.range.offset(0,2).setValue(getLastValue("B:B", e));
  }
}

function getLastValue(range, e) {
  var val =  e.source.getActiveSheet().getRange(range).getValues().filter ( function (d) {
    return d != "";
  });
  return val[val.length - 2];
}

Explained

We need to be in column C for anything to happen. In column D is shown the previous last entry of column A. This is done by feeding a helper function the corresponding range (A:A) and the object of the onEdit trigger (e). It filters the values for not empty ( != "") and passed on the previous last index of the array (return val[val.length - 2]). The same is done for column E.

Answer 2

In D1, copied across to E1 and the pair copied down to suit:

=if($C1<>"",max(A$1:A1),"")

should give results as shown in OP, whatever is entered into ColumnC (but provided something is).

IF
MAX