Google apps script - Broken for loop

Question

I'm working in Google apps script and seem to have screwed up one of my for loops. I'm sure that I am missing something trivial here, but I can't seem to spot it.

Code Snippet:

var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheets = ss.getSheets();
var lastRow = sheets[3].getLastRow();
var zw = sheets[3].getRange(2, 1, lastRow - 1, 26).getValues();
for (var j = 0; j < zw.length; ++j) {
    if (zw[j][9] === 'Yes') {
        var masterEmail = [];
        var firstLetterLastName = [];
        var first2Letter = [];
        var masterEmail.push(zw[j][22]);
        var firstLetterLastName.push(zw[j][1].charAt(0).toLowerCase());
        var first2Letter.push(zw[j][1].charAt(0).toLowerCase() + zw[j][1].charAt(1).toLowerCase());
        //The rest of the function follows...
    }
}

What's Not Working:

The for loop doesn't increment. When running the code in a debugger, var j stays at a value of 0.0, and the rest of the function only runs based of off the values in the 0 position of zw.

What I need it to do (AKA - How I thought I had written it:)

The ZW variable is holding a 2 dimensional array of cell values from a Google sheet. I'm looping through that, checking the 9th value of each array entry for a string of "Yes" and then running the rest of the function (for each column with a "Yes") if the condition is true.

I thought I had this working before, but recently had to restructure and optimize some things. Now I'm starting to think I may need to rethink things and use a different loop method. Can anyone educate me?

Edit: Here's a bit more context as requested:

function menuItem1() {
  var ui = SpreadsheetApp.getUi();
  var response = ui.alert('Are you sure you want to send emails?', ui.ButtonSet.YES_NO);
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheets = ss.getSheets();
  var lastRow = sheets[3].getLastRow();
  var zw = sheets[3].getRange(2, 1, lastRow - 1, 26).getValues();
    if (response === ui.Button.YES) {
      for (var j = 0; j < zw.length; j++) {
        if (zw[j][9] === 'Yes') {
          var firstLetterLastName = [];
          firstLetterLastName.push(zw[j][1].charAt(0).toLowerCase());
          //Other Stuff....
        }
      }
    }
}

I have a menu item attached to a simple onOpen, that calls menuItem1(). Calling the function prompts the user with a warning that they are about to send emails, then goes about getting data to assign email addresses based on the contents of the sheets. firstLetterLastName is an example.

I'm still not getting the loop to function, is it because I have it between two if statements? (Here is a link to the sheet)

could you show how the spreadsheet data looks like? Because there does not seem to be anything wrong with the for loop you've written. — Suyash Gandhi
I added an edit, does it provide the data you were looking for? — Jensen010
I made a copy of your spreadsheet, stripped the code out of your for loop and ifclauses and had no problem running your logic. If you aren't getting the expected results, I would focus on the code inside your for loop. If you would provide more information on what errors, if any, you're getting that would help us solve your problem. — Silinus
The error I'm getting is that [ j ] is staying at 0 instead of incrementing through the data I need it to - zw[j][9]. That corresponds to column...U? in the spreadsheet, which asks the client if they would like to send an email. var zw has all of the expected data (an array of arrays with all cell contents of each row, for each internal array item) I am trying to loop through that, determine whether there is a yes in column 9 of each row, and then run the function based on that. But, since [j] stays at 0, it will only look at one of those rows. Not an "error" per se, I've just done it wrong :) — Jensen010
I copied your file and started looking at your code. See my edits to the code in my copied file. — Karl_S

Vytautas Vytautas · Accepted Answer · 2017-01-27T05:24:05

Indeed it is quite trivial. You have mixed up your increment. You wrote

for (var j = 0; j < zw.length; ++j)

which means that you do 1 + i (and we know that at the start i = 0 which means your value will always be 1) instead of using the usual

for (var j = 0; j < zw.length; j++)

which would mean that you do i + 1 and update i, so you will get the expected 0 + 1 1 + 1 etc

EDIT:

First, I recommend instead of something like

if (responseMir === ui.Button.YES) {
  // Your For loop

doing

if (responseMir !== ui.Button.YES) {
  return
}

and in a similar fashion in the for loop

if (zw[j][9] !== 'Yes') {
  break
}

It mostly helps increase readability by not including large blocks of code under a single if, when all you want to do is to stop execution.

Your for loop gets broken because of the mistake here:

teacherEmailMir.push(selValsMir[j][7]);

So your loop will go over once. However on the next itteration, you try to push selValsMir[1][7] which does not exist. Note that each itteration you have var selValsMir = []; inside the loop, which means that for every j selValsMir will always be an empty array. So with the following line

selValsMir.push([zw[j][0], zw[j][1], zw[j][2], zw[j][3], zw[j][4], zw[j][5], zw[j][7], zw[j][22], zw[j][23], zw[j][24]]);

your array will always have selValsMir.lenght = 1 and selValsMir[0].length = 10. So obviously trying to access anything from selValsMir[1] will throw you an error and stop the script right there.

I also recommend looking over the if statements that look at the first and first 2 letters of the name as I believe you can accomplish the same with less code. Always try to streamline. Consider using switch() where you end up using a lot of else if

Google apps script - Broken for loop

1 Answers