如何创建可以在Google应用脚本中终止的错误功能

Question

In Google Sheets, I'm trying to create a checking function with Google Apps Script to ensure that certain cells are correctly filled up, and only if they're correctly filled up will the rest of the script run to update a separate table. In the code I've written, the updater function calls the checking function. The checking function correctly throws up an alert when the error is detected, but after the alert is closed, it returns to the updater function to wrongly run the update. What I'd like is for the code to just stop after the error alert is acknowledged. What am I doing wrong?

My code (vastly simplified; I actually check for many errors):

function updater() {
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('update');
  var lower = sheet.getRange(1, 1).getValue;
  var higher = sheet.getRange(2, 1).getValue;
  verify(lower, higher) //check that values are correctly input
  /* run below only if no errors */
  sheet.getRange(5, 1).setValue(lower);
  sheet.getRange(5, 2).setValue((lower + higher) / 2);
  sheet.getRange(5, 3).setValue(higher);
}

function verify(inLow, inHigh) {
  var ui = SpreadsheetApp.getUI();
  var err = 'X';
  if (inLow > inHigh) {
    err = 'Bottom value should be lower than Top value. Please re-enter.';
  }
  if(err == 'X') {
    return; //if there are no errors, return to updater()
  } else {
    ui.alert(err); //if there's an error, show an alert. want it to end here
  }
}

Answer 1

You can make your verify function return a boolean value that you can use in an if condition.

modified code below :

function updater() {
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('update');
  var lower = sheet.getRange(1, 1).getValue;
  var higher = sheet.getRange(2, 1).getValue;
  if(verify(lower, higher)){ //check that values are correctly input
  /* run below only if no errors */
  sheet.getRange(5, 1).setValue(lower);
  sheet.getRange(5, 2).setValue((lower + higher) / 2);
  sheet.getRange(5, 3).setValue(higher);
  }
}

function verify(inLow, inHigh) {
  var ui = SpreadsheetApp.getUI();
  var err = 'X';
  if (inLow > inHigh) {
    err = 'Bottom value should be lower than Top value. Please re-enter.';
  }
  if(err == 'X') {
    return true; //if there are no errors, return to updater()
  } else {
    ui.alert(err); //if there's an error, show an alert. want it to end here
    return false;
  }
}