Question

This is my very first day messing around with google script so excuse my limitations.

I was trying to write a function that deleted all the rows in a Form Spreadsheet while leaving the header row behind.

Why does this work:

  // Loop through the data in the range and delete the rows
if (data.length > 1) {
  for (var row = 1; row < data.length; row++) {
    ws.deleteRow(row+1);
    }
    ws.deleteRow(2); 

 }

While the following:

if (data.length > 1) {
  for (var row = 1; row < data.length; row++) {
    ws.deleteRow(row+1);
    }

  }

Leaves row 2 behind

Answer 1

Because the row indexes are 1-based (i.e., start at 1), you need to alter your for loop like this:

for (var row = 1; row <= data.length; row++) {

Assuming you have 2 rows, when you hit your second row in the loop (that is, when row = 2), the value of row will not be less than data.length (which is 2); it will be equal to the data.length. So with <, the test will fail and the code in the loop will not be executed that second time. With <= it will pass and code will be executed as desired.

This same pattern will of course happen with any number of rows.

EDIT: a few other problems:

Because the removal will happen immediately, the rows will all shift after a removal and will be numbered differently. This can be handled in a couple ways, but here’s one: change your deletion to start from the end and work backwards. so, now we have:

for (var row = data.length; row >= 1; row--) {

Also, if you’re only trying to skip the first row, as the header row, rather that change the index used (e.g., row + 1), just change where you start/stop your loop. this is simpler and more understandable. so, the loop becomes:

 for (var row = data.length; row >= 2; row--) {
    ws.deleteRow(row);
 }