Ignoring empty cells in Google Sheets custom script

Question

I am trying to create a formula to calculate Net Promoter Score on Google Sheets. I have the formula working but only when I specify the exact range. My issue is that this specific sheet will grow with data over time and I do not want to have to keep reselecting the range. What I want to do is select the entire row and just let it auto-update the NPS score. My issue with this approach is every empty cell is considered a zero which is screwing up my percentages. How can I make my function ignore the empty cells???

Here is my attempt:

 /** This is a custom formula that calculates the Net Promoter Score. @customFunction */ function NPS(numArr) { var detractors = new Array(); var passive = new Array(); var promoters = new Array(); var i = 0; for (i = 0; i < numArr.length; i++) { if (isNaN(numArr[i])) { console.log(numArr[i]); } else { if (numArr[i] >= 9) { promoters.push(numArr[i]); } else if (numArr[i] === 7 || numArr[i] === 8) { passive.push(numArr[i]); } else if (numArr[i] <= 6) { detractors.push(numArr[i]); } } } var promoPercentage = promoters.length / numArr.length; var detractorsPercentage = detractors.length / numArr.length; return (promoPercentage - detractorsPercentage) * 100; }

Answer 1

You can use JavaScript filter [1] function to filter the empty values from the array you're getting ( numArr ). Also, notice that you're selecting a range of cells so the argument will be a 2D array [2], where each value is a "row" array filled with the column values for that row, in case you just want the first value of each row (for a one column range like A1:A25) you need to access the first element of each "row" array to get the actual value:

function NPS(numArr) {

  var detractors = new Array();
  var passive = new Array();
  var promoters = new Array();

  var i = 0;

  //Filter empty elements
  numArr = numArr.filter(function(element) {
    return element[0] !== '';
  })

  for (i = 0; i < numArr.length; i++) {
    if (isNaN(numArr[i][0])) {
      console.log(numArr[i][0]);
    } else {
      if (numArr[i][0] >= 9) {
        promoters.push(numArr[i][0]);
      } else if (numArr[i][0] === 7 || numArr[i][0] === 8) {
        passive.push(numArr[i][0]);
      } else if (numArr[i][0] <= 6) {
        detractors.push(numArr[i][0]);
      }
    }
  }

  var promoPercentage = promoters.length / numArr.length;
  var detractorsPercentage = detractors.length / numArr.length;

  return (promoPercentage - detractorsPercentage) * 100;
}

[1] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

[2] https://developers.google.com/apps-script/guides/sheets/functions#arguments