Google Apps Script snippet to manage and store persistent state. Uses both Firebase (FirebaseApp library), CacheService and BBLog for logging.

Properties_.gs

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// JSHint - TODO
/* jshint asi: true */

(function() {"use strict"})()

// Properties_.gs
// ==============
//
// A utility module to manage and store persistent state.
// Leverages both Firebase and CacheService.
// 
// All property values are processed as JSON serialized strings.

var Properties_ = (function(ns) {

  ns.SIX_HOURS_IN_SECONDS = 6 * 60 * 60

  /**
   * Retrieve the property from persistent storage
   *
   * @param {string} oldKey Key used to retrieve the property
   */
   
  ns.getProperty = function(oldKey) {
  
    Log_.functionEntryPoint()
    
    var newKey = updateKey(oldKey)    
    var cached = Cache_.get(newKey)
    
    if (cached === null) {
      cached = Firebase_.getData(newKey)
      cached && Cache_.put(newKey, cached, ns.SIX_HOURS_IN_SECONDS)
    }
    
    return cached
     
  } // Properties_.getProperty()
  
  /**
   * Puts a property into persistent storage
   *
   * @param {string} key Key used to name and store the property
   * @param {string} value Value of the property
   * @param {boolean} addToFirebase If true cached values are mirrored in properties object [OPTIONAL, DEFAULT true]
   */
   
  ns.setProperty = function(oldKey, value, addToFirebase) {
  
    Log_.functionEntryPoint()

    value = (typeof value === 'string') ? value : JSON.stringify(value)

    var newKey = updateKey(oldKey)
    addToFirebase = (typeof addToFirebase === 'undefined') ? true : addToFirebase
    
    if (addToFirebase) {
      Firebase_.setData(newKey, value)
    }
    
    Cache_.remove(newKey)   
    Cache_.put(newKey, value, ns.SIX_HOURS_IN_SECONDS)    
    
  } // Properties_.setProperty()
  
  /**
  * Removes a property from persistent storage
  *
  * @param {string} oldKey Key used to reference a stored property
  * @param {boolean} removeFromFirebase If true cached values are removed from properties object.
  */
  
  ns.deleteProperty = function(oldKey, removeFromFirebase) {
  
    Log_.functionEntryPoint()
    
    removeFromFirebase = removeFromFirebase || true
    var newKey = updateKey(oldKey)
    
    Cache_.remove(newKey)
    
    if (removeFromFirebase) {
      Firebase_.removeData(newKey)
    }
    
  } // Properties_.deleteProperty()

  /**
   * Add the user path to the key
   *
   * @param {string} oldKey
   *
   * @return {string} newKey
   */
  
  function updateKey(oldKey) {
  
    Log_.functionEntryPoint()    
    return USERS_KEY_PREFIX + '/' + Utilities.base64EncodeWebSafe(User_) + '/' + oldKey
  
  } // Properties_.updateKey() 

  return ns

})(Properties_ || {})