Use e.oldValue with delete Key - google-apps-script

Question

Hello I am currently working on a time tracking system. With the following code I track the time how long a value was in a cell. This time is recorded in another worksheet and this is done continuously by appendRow ().
function onEdit(e) {
addTimestamp(e);
}
function addTimestamp(e) {
var ui = SpreadsheetApp.getUi();
var ws = "Tabellenblatt2";
var ss = e.source;
var targetSheet = ss.getSheetByName("Tabellenblatt1");
var range = targetSheet.getRange(3, 2, 1000, 1);
var currentDate = new Date();
if (e.source.getActiveSheet().getName() === ws && range != "") {
var val = e.range.getValue();
if (val != "") {
let rowToAdd = [val, "", currentDate, ""]
ss.getSheetByName("Tabellenblatt1").appendRow(rowToAdd);
ui.alert("Test2");
} else {
var sheet = ss.getSheetByName("Tabellenblatt1");
var dataFinder = sheet.createTextFinder(e.oldValue);
var nameRow = dataFinder.findAll()[0].getRow();
sheet.getRange(nameRow, 4).setValue(currentDate);
ui.alert("Test3");
}
}
}
Currently I cannot delete the content of the cell with the delete key, otherwise e.oldValue is undfined and I cannot get the date in the first worksheet. Now I always have to go to the formula area, mark the text in the cell and delete it. Is there a way to use the whole thing with the delete key anyway?

Answer 1

Unfortunately you cannot have the property oldValues if you use del or backspace button. According to Tanaike's comment here, there are certain scenarios where values and oldValues would appear in the event object.
In the case for editing a value to empty cell
e.value is included in e.
e.oldValue is NOT included in e.
In the case for overwriting a cell with a value by other value
Both e.value and e.oldValue are included in e.
In the case for deleting a value from a cell with a value
Both e.value and e.oldValue are NOT included in e.
Values of event object in multiple scenarios:
Adding value to an empty cell:
Overwriting a cell:
Deleting a value from a cell with a value:
A workaround would be creating a macro or button that will save and delete the value of the cell.
Example:
Code:
// this function will delete and display value of the active cell
function deleteCell(){
var sh = SpreadsheetApp.getActiveRange();
var oldValue = sh.getValue();
sh.clear();
Browser.msgBox(oldValue);
}
Button:
References:
Creating macros in Apps Script
Add A Google Sheets Button To Run Scripts