Properties in Google Apps Script is confusing. At least it was for me. I honestly spent a year avoiding using properties, I found saving variables as properties very frustrating. I use properties often and wanted to make a quick introduction to how properties in Apps Script work.

How to Save a Property Video

// Kurt Kaiser
// kurtkaiser.us
// All Rights Reserved, 2019
var scriptProperties = PropertiesService.getScriptProperties();

function onOpen(){
  var ui = SpreadsheetApp.getUi();
  var response = ui.prompt('What is your favorite color?', ui.ButtonSet.OK);
  scriptProperties.setProperty('color', response.getResponseText());
  ui.alert('Favorite color: ' + scriptProperties.getProperty('color'));
}

function myAlert(){
  var ui = SpreadsheetApp.getUi();
  ui.alert('Favorite color: ' + scriptProperties.getProperty('color'));
}