Inner For Loop not executing in App Script

Question

Context

In google app script for gsheets I am running this function that searches the names of items in a comma separated list within a single cell per row, against a list of item name and ids in 2 columns.

The function is called within another function that iterates through each row of data in the Data Table.

The goal is to replace the names with the ids in a comma separated list.

The Problem

The nested loop just doesn't run! When I set up training outputs to test where the code gets blocked it's at the inner for loop, it breaks at that line and doesn't execute at all. I cannot figure out why that would be as I can't see a problem with my syntax.

Any ideas where I could be going wrong please?

The data looks like this:

Item Directory Table:

Item ID | Item Name
--------------------
1234    | Item 1
46976   | Item 2
3526    | Item 3
32255   | Item 4
425     | Item 5  


Data table:

Data Name | Items
--------------------
Row 1     | Item 1, Item 2, Item 5
Row 2     | Item 5, Item 2
Row 3     | Item 4
Row 4     | 
Row 5     | Item 1

Desired output:

Row 1 = [1234, 46976, 425] // updated item 2
Row 2 = [425, 46976]
Row 3 = [32255]
Row 4 = []
Row 5 = [1234]

This is my function:

function findItems(x) {
  var items = [];
  var j = 0;
  var i = 0;
  var itemNames = Items.getRange(2 ,11).getValue().split(', ');
  var itemIDs = Items.getRange(3 ,11).getValue().split(', ');
  
  if (data.getRange(x, 6).getValue() != '') {
    items = data.getRange(x, 6).getValue().split(', ');
    for (i = 0; i < items.length; i++) {
      output.getRange(2, 1).setValue(items[i]);
      for (j = 0; j < itemNames.length; j++) {
       if (items[i] === itemNames[j]) {
          items[i] = itemIDs[j];
        }
      }
    }
  }
  return items
}

Answer 1

What I will provide below is a one-time run for all rows. Feel free to modify to get your expected behavior, you can add a parameter or call the function as formula to populate the cells one by one.

function findItems() {
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  var lastRow = sheet.getLastRow();
  var ids = sheet.getRange('A2:A' + lastRow).getValues().flat();
  var names = sheet.getRange('B2:B' + lastRow).getValues().flat();
  var data = sheet.getRange('C2:C' + lastRow).getValues().flat();
  var items = sheet.getRange('D2:D' + lastRow).getValues();

  items.forEach(function(item, count){
    var elems = item[0].split(",");
    for(var i = 0; i < elems.length; i++){
      for(var j = 0; j < names.length; j++){
        if(elems[i].trim() == names[j].trim()){
          elems[i] = ids[j];
          break;
        }
      }
    }    
    // separated the formatting so you can easily modify here
    // followed the formatting in your post
    var output = data[count] + ' = [' + elems.join(', ') + ']';
    sheet.getRange('E' + (count + 2)).setValue(output);
  });
}

This is the expected output from this code.

If you want to return something, you might want to modify the code above as this only sets the string output as the cell's value.

Logic is pretty straight forward, but if you have any clarifications/questions, feel free to comment below.