Loop through specific columns and setting value - loops

Question

I have a script but it works pretty slow and Im trying to see if I could make it work faster by possibly making it loop through the columns 10,12,15,17,20,22,25,27,30,32,35,37,40,42,45,47,50,52,55,57 instead of writing an if statement for each column. The way I currently have it works but it's slow and looks like this
var s = SpreadsheetApp.getActiveSheet();
if( s.getName() == "Student Data-NEA" ) { //checks that we're on the correct sheet
var r = s.getActiveCell();
if( r.getColumn() == 10 && r.getValue() == 'P') { //checks the column
var nextCell = r.offset(0, 1);
//if( nextCell.getValue() !== '' ) //is empty?
nextCell.setValue("P- N/A");
}
if( r.getColumn() == 12 && r.getValue() == 'P') { //checks the column
var nextCell = r.offset(0, 1);
//if( nextCell.getValue() !== '' ) //is empty?
nextCell.setValue("P- N/A");
}
if( r.getColumn() == 15 && r.getValue() == 'P') { //checks the column
var nextCell = r.offset(0, 1);
//if( nextCell.getValue() !== '' ) //is empty?
nextCell.setValue("P- N/A");
}
if( r.getColumn() == 17 && r.getValue() == 'P') { //checks the column
var nextCell = r.offset(0, 1);
//if( nextCell.getValue() !== '' ) //is empty?
nextCell.setValue("P- N/A");
}
Etc.
What it does is it looks at a column and if there is a P then it offsets 1 column and pastes a P- N/A. Could someone help making the script shorter so it can run faster? Thank you.

Answer 1

You need to use getValues(range). This way you get an array. You can process this array and then use setValues(range) to fill all cells in the range at once with values of the array. It will work much faster.
Probably something like this:
function main() {
var s = SpreadsheetApp.getActiveSheet();
if (s.getName() != "Student Data-NEA") return;
var r = s.getActiveCell(); // current cell
var row = r.getRow(); // index of current row
var row_range = s.getRange("A"+row+":Z"+row); // get range of the row
var row_values = row_range.getValues().flat(); // get array [cell, cell, cell]
var value = "P- N/A";
// change the array (not the sheet)
if (row_values[9] == "P") row_values[10] = value;
if (row_values[11] == "P") row_values[12] = value;
if (row_values[14] == "P") row_values[15] = value;
if (row_values[16] == "P") row_values[17] = value;
// change the sheet
row_range.setValues([row_values]); // set all values for the row at once
}
If your conditions all the same, you can loop through list of columns this way:
var condition = "P";
var columns = [9, 11, 14, 16];
for (var col of columns) {
if (row_values[col] == condition) row_values[col+1] = value;
}
// instead of this
// if (row_values[9] == "P") row_values[10] = value;
// if (row_values[11] == "P") row_values[12] = value;
// if (row_values[14] == "P") row_values[15] = value;
// if (row_values[16] == "P") row_values[17] = value;
Update
I don't know why I do it, since the author of the question still provided almost no information about what he does with the table and we have no sample of the table, etc. But whatever:
If you need to change next cell to "P- N/A" (do you need it? I still have no idea) in some columns if edited cell contains "P", here is a script:
function onEdit(e) {
var s = e.source.getActiveSheet();
if (s.getName() != "Student Data-NEA") return;
var col = e.range.columnStart;
var row = e.range.rowStart;
var range = s.getRange(row,col,1,2);
var range_array = range.getValues();
var cell_value = range_array[0][0];
var next_cell_value = "P- N/A";
var cols = [10, 12, 15, 17];
if (cell_value == "P" && cols.includes(col)) {
range_array[0][1] = next_cell_value;
range.setValues(range_array);
}
}
But actually it can be done much easier and faster with standard Excel-like function (example for the cell "K1"):
=IF(EQ(J1,"P"),"P- N/A","")
Just populate with this function the columns K, M, P, R...