How to increment simple formula by 1 in Google Apps Script? - google-apps-script

Question

Disclaimer: I'm a Google Apps Script newbie.
I'm trying to create a timesheet in Google Sheets that lets a user clock in & clock out to log hours on a given project. I've borrowed code from a YouTube video on the general structure of setting the whole thing up.
Here's what the blank time sheet looks like. It's pretty basic:
I've created a user button (off to the right) where the user presses "Start" and cell A2 will input a timestamp. Then the user can press an "End" button, and a second timestamp, this time in B2, will appear, along with a simple calculation in C2 that measures the delta in the two timestamps, thus giving a duration of time spent on a given task or project. Here's what it looks like:
When the user needs to press "Start" again, a new timestamp appears in cell A3, and so on so forth, along with a new delta calculation for each new row.
Problem: I'm unable to get the simple delta calculation in column C to increment down each new rows so that the setFormula function doesn't contain hardcoded references to cells A2 & B2. See below code for what I have so far:
function setValue(cellName, value) {
SpreadsheetApp.getActiveSpreadsheet().getRange(cellName).setValue(value);
}
function getValue(cellName) {
return SpreadsheetApp.getActiveSpreadsheet().getRange(cellName).getValue();
}
function getNextRow() {
return SpreadsheetApp.getActiveSpreadsheet().getLastRow() + 1;
}
function addStartRecord (a) {
var row = getNextRow();
setValue('A' + row, a);
}
function addEndRecord (b, c) {
var row = getNextRow()-1;
setValue('B' + row, b);
setValue('C' + row, c);
}
function punchIn() {
addSRecord(new Date());
}
function punchOut() {
addERecord(new Date(), '=B2-A2');
}
The problem is with the punchOut() function there at the bottom. Any idea on the best way to increment this delta calculator down each new row?
Note: I saw a pretty good answer to a similar question here, but the code is throwing an error in the script editor after the line containing data[i] = ['=A' + i+1.toString() + ' + 1 ' ]. Also, I don't want to set a definitive last row for the delta calculation (such as 20 in this example). I'd want the user to be able to record as many new start/end times for a project as they'd want.
Edit: Here's a link to the timesheet so you can test the code.

Answer 1

Try modifying your punchOut method like this:
function punchOut() {
var ss = SpreadsheetApp.getActiveSheet();
var row = ss.getLastRow();
addEndRecord(new Date(), '=B' + row + '-A' + row);
}
I tested it in the sheet and it worked well.

Answer 2

setFormula() - this enables you to describe the formula to be inserted into column C.
The following is two simple functions that handle "Punch in" and "Punch Out" (with its calculation).
function so5695101401in() {
// punchin
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getActiveSheet();
var lR = sheet.getLastRow();
// Logger.log("DEBUG: the last row is "+lR);
var punchinRange = sheet.getRange(lR+1, 1);
// Logger.log("DEBUG: the punchinRange = "+punchinRange.getA1Notation());
punchinRange.setValue(new Date());
}
function so5695101401out() {
// punchout
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getActiveSheet();
var lR = sheet.getLastRow();
//Logger.log("DEBUG: the last row is "+lR);
var punchoutRange = sheet.getRange(lR, 2);
// Logger.log("DEBUG: the punchoutRange = "+punchoutRange.getA1Notation());
punchoutRange.setValue(new Date());
var timeElapsed = sheet.getRange(lR, 3).setNumberFormat("hh:mm:ss");
timeElapsed.setFormula("=B2-A2");
}
setFormula

Answer 3

I use a workaround for this problem, via app script copy the cell with the formula to de new row or range!.
for you problem:
var formula1 = sheetDatos.getRange(lastRow, 3); //get the formula
var copyRange = sheetDatos.getRange(lastRow+1, 3);
formula1.copyTo(copyRange);
for me is more easy in this way, try to do in sheet to understand how this work.
you need a initial formula to go in this way ;)