I want to use a macro to check a value in a sheet and return one of two values

Question

I have three tabs on my Google Sheets - called "Credentials", "Credentials-fullsales" and "Credentials-reservations" I need a Macro that goes to each of those tabs, checks the contents of cell B4. If there is a "1" in there, it needs to change it to "2". If there is a "2" in there, it needs to change it to "1"

On the face of it pretty simple, but I have't done much Macro coding and my skillset is extremely low!

Below is the code I've been trying, but it gives me a "range is not defined" error. Any ideas or tips?

TIA

function UntitledMacro3() {
  var spreadsheet = SpreadsheetApp.getActive();
  spreadsheet.setActiveSheet(spreadsheet.getSheetByName('Credentials'), true);
  spreadsheet.getRange('B4').activate();
  var value = range.getValue();
  if (value == 1) {
    range.setValue(0);
  } else if (value == 0) {
    range.setValue(1);
  }
var spreadsheet = SpreadsheetApp.getActive();
  spreadsheet.setActiveSheet(spreadsheet.getSheetByName('Credentials-reservations'), true);
  spreadsheet.getRange('B4').activate();
  var value = range.getValue();
  if (value == 1) {
range.setValue(0);
  } else if (value == 0) {
range.setValue(1);
  }
  var spreadsheet = SpreadsheetApp.getActive();
  spreadsheet.setActiveSheet(spreadsheet.getSheetByName('Credentials-fullsales'), true);
  spreadsheet.getRange('B4').activate();
  var value = range.getValue();
  if (value == 1) {
    range.setValue(0);
  } else if (value == 0) {
    range.setValue(1);
  }
  }

Answer 1

You can try this;

function checkData(){
  var spreadsheet = SpreadsheetApp.getActive();

  var sheetnames = ['Credentials', 'Credentials-reservations', 'Credentials-fullsales'];

  sheetnames.forEach(function (shName) {
    var sheet= spreadsheet.getSheetByName(shName);
    var data= sheet.getRange('B4').getValue();

    if (data==1){
      sheet.getRange('B4').setValue(0);
    } else {
      sheet.getRange('B4').setValue(1); 
    }
    })
}