Detect formula errors in Google Sheets using Script

Question

My ultimate goal is here, but because I've gotten no replies, I'm starting to learn things from scratch (probably for the best anyway). Basically, I want a script that will identify errors and fix them

Well, the first part of that is being able to ID the errors. Is there a way using Google Script to identify if a cell has an error in it, and return a particular message as a result? Or do I just have to do an if/else that says "if the cell value is '#N/A', do this", plus "if the cell value is '#ERROR', do this", continuing for various errors?. Basically I want ISERROR(), but in the script

Answer 1

Use a helper function to abstract away the nastiness:

function isError_(cell) {
  // Cell is a value, e.g. came from `range.getValue()` or is an element of an array from `range.getValues()`
  const errorValues = ["#N/A", "#REF", .... ];
  for (var i = 0; i < errorValues.length; ++i)
    if (cell == errorValues[i])
      return true;

  return false;
}

function foo() {
  const vals = SpreadsheetApp.getActive().getSheets()[0].getDataRange().getValues();
  for (var row = 0; row < vals.length; ++row) {
    for (var col = 0; col < vals[0].length; ++col) {
      if (isError_(vals[row][col])) {
        Logger.log("Array element (" + row + ", " + col + ") is an error value.");
      }
    }
  }
}

Using Array#indexOf in the helper function:

function isError_(cell) {
  // Cell is a value, e.g. came from `range.getValue()` or is an element of an array from `range.getValues()`
  // Note: indexOf uses strict equality when comparing cell to elements of errorValues, so make sure everything's a primitive...
  const errorValues = ["#N/A", "#REF", .... ];
  return (errorValues.indexOf(cell) !== -1);
}

If/when Google Apps Script is upgraded with Array#includes, that would be a better option than Array#indexOf:

function isError_(cell) {
  // cell is a value, e.g. came from `range.getValue()` or is an element of an array from `range.getValues()`
  const errorValues = ["#N/A", "#REF", .... ];
  return errorValues.includes(cell);
}

Now that the v8 runtime is available, there are a number of other changes one could make to the above code snippets (arrow functions, etc) but note that changing things in this manner is not required.