How to define global variable in Google Apps Script

Question

I see most examples from Google is they use only functions in a single giant script.

e.g. https://developers.google.com/apps-script/quickstart/macros

But in

Answer 1

I'm using a workaround by returning a function with an object of my global variables:

function globalVariables(){
  var variables = {
    sheetName: 'Sheet1',
    variable1: 1,
    variable2: 2
  };
  return variables;
}

function functionThatUsesVariable (){
  var sheet =   SpreadsheetApp.getActiveSpreadsheet().getSheetByName(globalVariables().sheetName);
}