Cannot convert NaN to (class) - google-apps-script

Question

While writing a Google Apps Script, I ran across this error:
"Cannot convert NaN to (class). (line 19, file "Code")
The line in question:
pos[pos.length] =
ss.getSheets()[sheetNumber + 13].getRange(teamRow + i, teamCol + 1).getValue();
I searched stackoverflow, but the best I could find was that "getRange" wasn't being passed integers. However, I derived the teamRow and teamCol from integers, and i is an index for a for loop, also an integer.
This error only appears when I call my function through another function.
Final question: what does the error mean, and what can I do to fix it?

Answer 1

NaN means Not a Number. It is basically used in floating point arithmetic to significate that a value cannot be expressed using the convention. You can look for IEEE 754 to get more details.
Your error message informs you that, in your script, you are using a NaN value in an expression that forbids it.
To track it, you could make your life simplier in using local variables to store intermediate values. Then you'll be able to inspect them either using the debugger or by logging them, as suggested in a comment.
For instance :
var allSheets = ss.getSheets();
var targetSheetIndex = sheetNumber + 13;
var targetSheet = allSheets[targetSheetIndex];
var targetRow = teamRow + i;
var targetCol = teamCol + 1;
var targetCell = targetSheet.getRange(targetRow, targetCol);
var targetValue = targetCell.getValue();
Using this technique you can identify where your code may fail and prevent it from failing by guarding it with tests (existence tests, boundary tests, …). After that, you can reassemble your code, either using your original single line or a balance between a single line and the above splitting example.