When converting from VBA, unless you are abandoning VBA, it’s just as well to mimic some of the functions that are missing from GAS so that you can minimize your script Conversion work. Here is a selection of useful ones for quick reference. Since javaScript is case sensitive, be careful that you get it right. I have retain the official VBA convention for case for existing (mimicked) VBA functions, rather than the usual javaScript convention.

This is now part of a Google Apps Script shared library you can incorporate in your own project.

Code
This code is here, and the shared Google Apps Script Library can be accessed with the key MEQ3tE5y5_cTOAgUbUKSIAiz3TLx7pV4j

Code

The code is in the mcpher library. See here for how to incorporate it into your project.

/**
 * @static
 */
var dbSilo;
function createDbSilos(optionalDb){
  return dbSilo ? 
      dbSilo : 
      (dbSilo = new cScriptDbSilo(optionalDb));
}
function librarySiloDb() {
  return ScriptDb.getMyDb();
}
/**
 * a cScriptDbSilo
 * @class 
 * @param {ScriptDbInstance} Db the default scriptDB
 * @implements {cScriptDbSilo}
 * @return {cScriptDbSilo} a new cScriptDbSilo
 */
function cScriptDbSilo(optionalDb) {
// create a Silo for known script silos
  this.xSilos = new collection();
  this.silos = function () {
    return this.xSilos;
  };
  this.xDb = IsMissing(optionalDb) ?  librarySiloDb() : optionalDb;
  return this;
}
/**
 * return the db silo item associated with the given key
 * @param {string} k the key
 * @param {ScriptDbInstance=} optionalDb the default scriptDB (default the db for the silo collection)
 * @param {boolean=} createIfUnknown whether to create the item if it doesnt exist (default true)
 * @param {boolean=} optionalHash whether to encrypt the userstamp
 * @param {boolean=} optionalMeOnly whether to filter by only records that I created
 * @return {cScriptDbSiloItem} the cScriptDbSiloItem
 */
function scriptDbSilo(k,optionalDb,createIfUnknown,optionalHash,optionalMeOnly) {
// find the Silo associated with this key
    // get the item or create it
    var dbSilo = createDbSilos(optionalDb);
    if (IsMissing(k)) 
      return dbSilo;
    else {
      var silo = dbSilo.silos().item(k,false);
    // return the SiloItem, or create one if it's allowed
      return silo ? silo : (fixOptional (createIfUnknown,true) ?  dbSilo.init(k,optionalDb,optionalHash,optionalMeOnly) : null) ;
    }
}
/**
 * add db silo item associated with the given key
 * @param {string} k the key
 * @param {ScriptDbInstance=} optionalDb the default scriptDB (default the db for the silo collection)
 * @param {boolean=} optionalHash whether to encrypt the userstamp
 * @param {boolean=} optionalMeOnly whether to filter by only records that I created
 * @return {cScriptDbSiloItem} the cScriptDbSiloItem
 */
cScriptDbSilo.prototype.init = function (k,optionalDb,optionalHash,optionalMeOnly) {
  return this.silos().add (new cScriptDbSiloItem(k,this,optionalDb,optionalHash,optionalMeOnly),k);
};
/**
 * remove all db silo items for this db
 * @param {object} ob the query by example object
 * @param {ScriptDbInstance=} optionalDb the default scriptDB (default the db for the silo collection)
 * @return {cScriptDbSilo} the cScriptDbSilo
 */
cScriptDbSilo.prototype.remove = function (ob,optionalDb) {
  return this.removeData(ob,optionalDb);
}
/**
 * remove db silo item data associated with the given query object
 * @param {object} ob the query by example object
 * @param {ScriptDbInstance=} optionalDb the default scriptDB (default the db for the silo collection)
 * @return {cScriptDbSilo} the cScriptDbSilo
 */
cScriptDbSilo.prototype.removeData = function (ob,optionalDb) {
    var qob = fixOptional(ob,{});
    //-- disabled for now---only allowed to delete your own data
    //qob.userStamp = Session.getUser().getEmail();
    //if (this.xHash) qob.userStamp = shortKeyHash(qob.userStamp);
    var db = fixOptional(optionalDb, this.xDb);
    // we'll use removeBatch
    while(true) {
      var result = db.query(qob); // get everything, up to limit
      if (result.getSize() == 0) {
        break;
      }
      var o = [];
      while (result.hasNext()) {
        if (o.length > this.xBatchMax) {
          DebugAssert(db.allOk(db.removeBatch(o, false)), "failed to delete " + o.length + " objects"); 
          o = [];
        }
        o.push(result.next());
      }
      if (o.length > 0 ) {
        var result = db.removeBatch(o, false);
        DebugAssert(db.allOk(result), "failed to delete " + o.length + " objects"); 
      }
    }
  return this;
}
/**
 * fill the silos from the data in the script DB
 * @param {object} ob the query by example object
 * @param {ScriptDbInstance=} optionalDb the default scriptDB (default the db for the silo collection)
 * @return {cScriptDbSilo} the cScriptDbSilo
 */
cScriptDbSilo.prototype.fill = function (optionalDb) {
// fill Silo with every known silo  in the given db
    var db = fixOptional ( optionalDb, this.xDb);
    var result = db.query({}); //note-- only works up to the limit
      while (result.hasNext()) {
        var k = result.next().siloId;
        if ( ! this.Silos.item(k,false) ) 
          this.Silos().add (new cScriptDbSiloItem(k,this,db),k ); 
      }
  return this;
};
/**
 * a cScriptDbSiloItem
 * @class 
 * @param {string} k the key
 * @param {cScriptDbSilo=} parent the collection of silo items
 * @param {boolean=} optionalHash whether to encrypt the userstamp
 * @param {boolean=} optionalMeOnly whether to filter by only records that I created
 * @implements {cScriptDbSiloItem}
 * @return {cScriptDbSiloItem} a new cScriptDbSiloItem
 */
function cScriptDbSiloItem(k,parent,optionalDb,optionalHash,optionalMeOnly) {
  // a silo item
  this.xBatch = [];
  this.xKey = makeKey(k);
  this.xParent = parent;
  this.xHash = fixOptional( optionalHash, false);
  this.xMeOnly = fixOptional( optionalMeOnly, false);
  this.xDb = fixOptional( optionalDb , this.xParent.xDb);
  this.db = function() {
    return this.xDb;
  }
  // this is wont change in a silo session so may as well do it once
  this.xWho = this.who();
  // there is a bug in savebatch that failes for more than about 4000
  // here's a workaround
  this.xBatchMax = 4000;
  return this;
}
/**
 * construct the query object that identifies this query by example
 * @param {object=} ob the query by example (default all data)
 * @return {object}  a query by example to silo the data
 */
cScriptDbSiloItem.prototype.querySet = function(ob) {
  // apply a query for this silo
  var newOb = fixOptional(ob,{});
  newOb.siloId = this.xKey;
  if (!newOb.userStamp && this.xMeOnly) newOb.userStamp = this.xWho;
  return newOb ;
};
cScriptDbSiloItem.prototype.queryStamp = function(ob) {
  // apply a user and time stamp
  ob.timeStamp = new Date().getTime();
  ob.userStamp = this.xWho;
  return ob;
};
/**
 * do a query within the silo for this cScriptDbSiloItem
 * @param {object} [ob={}]  the query by example (default all data)
 * @param {object} [ob={}]  the query by example (default all data)
 * @return {ScriptDBquery} a query by example to silo the data
 */
cScriptDbSiloItem.prototype.query = function(ob) {
  return this.db().query(this.querySet(ob));
};
/**
 * do a query within the silo and put to an array, taking account of limits
 * @param {object} [ob={}]  the query by example (default all data)
 * @param {object} [ob={}]  the query by example (default all data)
 * @param {number} [optLimit=0]  default bypass any limits
 * @return {Array} an array of results
 */
cScriptDbSiloItem.prototype.queryArray = function(ob, optLimit) {
  // this is the max I'll take in one go to be compatible with parse.com
  var maxLimit = 1000;
  var limit = fixOptional ( optLimit, 0);
  var results =[], q = this.querySet(ob);
  while(true) {
    var qr =  this.db()
                .query(q)
                .limit(limit > 0 ? limit-results.length : maxLimit).startAt(results.length);
    // we're done
    if (!qr.hasNext()) return results;
    // still have pushing to do
    while(qr.hasNext() && (limit==0 || results.length < limit)) results.push(qr.next());
  }
};
/**
 * do a count query within the silo for this cScriptDbSiloItem
 * @param {object} &#91;ob={}&#93; the query by example (default all data)
 * @return {ScriptDBquery} a query by example to silo the data
 */
cScriptDbSiloItem.prototype.count = function(ob) {
  return this.db().count(this.querySet(ob));
};
/**
 * do a save within the silo for this cScriptDbSiloItem
 * @param {object} ob the data so save
 * @param {boolean} optBatch whether or not to save up for a batch update
 * @return {ScriptDbResult} a query result 
 */
cScriptDbSiloItem.prototype.save = function(ob,optBatch) {
  var sob = this.queryStamp(this.querySet(ob));
  if (fixOptional (optBatch, false)) {
    if (this.batchLength() > this.xBatchMax) {
      this.saveBatch();
    }
    this.xBatch.push(sob);
  }
  else
    return this.db().save(sob);
};
/**
 * provide current batch length 
 * @return {number} the batch length
 */
cScriptDbSiloItem.prototype.batchLength = function() {
  return this.xBatch ? this.xBatch.length : 0;
};
/**
 * clear out any batch items
 * @return {ScriptDbResult} a query result 
 */
cScriptDbSiloItem.prototype.saveBatch = function() {
   if (this.xBatch.length) {
     var results = this.db().saveBatch(this.xBatch, false);
     this.xBatch = [];
     return results;
   }
   else 
     return null;   
};
/**
 * do a save within the silo for this cScriptDbSiloItem, and delete the data
 * @param {object=} ob the data so remove (default all data for this silo)
 * @return {cScriptDbSiloItem} the cScriptDbSiloItem
 */
cScriptDbSiloItem.prototype.remove = function(ob) {
  return this.xParent.removeData(this.querySet(ob),this.db());
};
/**
 * get who user is, and hash email address if required
 * @param {boolean=} optHash whether to encrypt, otherwise use the silo default
 * @return {string} the user email or hashed emaik
 */
cScriptDbSiloItem.prototype.who = function(optHash) {
  return fixOptional(optHash, this.xHash) ? shortKeyHash(Session.getUser().getEmail()) : Session.getUser().getEmail();
};
/**
 * return the stuff from the db associated with the e.parameter.entry value
 * @param {String} siloNamethe the locker name
 * @param {scriptDB} db the private db to use
 * @return {ContentService} the rest response
 */
function getMyStuff (siloName, db) {
    var response = {status: {code:"bad", reason:"entry parameter not found"}, result:null};
    var silo = scriptDbSilo(siloName,db);
    var thisMail = silo.who();
    if (!db) {
      response.reason = "private db must be specified" ;
    }
    else if (siloName) 
    { var q=  silo.query();
      if (q.hasNext()) {
        // only retrievable by teh same user as created it
        var result = q.next();
        try {
           if (result.userStamp != thisMail) {
             response.status.code = "bad";
             response.status.reason = siloName + "does not belong to you";
           }
           else {
             response.status.code = "good";
             response.status.reason = siloName + " found in your stuff";
             response.result = result;
           }
          }
          catch (err) {
            response.status.code = "bad";
            response.status.reason = err;
          }
      } 
      else {
        response.status.code = "bad";
        response.status.reason = siloName + " not found in your stuff";
      }
    }
    return response;
}
/**
 * create an entry for the given siloname value
 * @param {String} siloNamethe the locker name
 * @param {scriptDB} db the private db to use
 * @param {object} content the content to store
 * @return {scriptDBObject} the saved object
 */
function createStuff (siloName, db, content) {
  // exist?
  DebugAssert(db, "you must provide a db");
  var silo =  scriptDbSilo(siloName,db);
  var myAuth = silo.query();
  if (myAuth.hasNext()) silo.remove();
  var put = {};
  put.myStuff = content;
  put.help = "for details see ramblings.mcpher.com";
  return silo.save(put);
}
/** react to a doGet(e) using lockbox for oAuth
 * @param {object} e as passed to doGet() (show or oauth)
 * @param {scriptDBInstance} db the private db to use
 * @return {String} the json string content
 */
function getStuffContent (e,db) {
   //parameters 
   // e.parameter.entry - the lockBox entry name
   // e.parameter.proxyUrl - optional - if specifed then proxyUrl to execute , using lockbox entry for oAuth 
   // e.parameter.action - manadatory - (not implemented yet edit,)show,oauth
  var content ="";
  if(IsMissing(db)) 
    content = JSON.stringify ({error: "programming error - you must provide a scriptDB to use"}) ;
 else {
    var entry =  decodeURIComponent(e.parameter.entry)
    var proxyurl = decodeURIComponent(e.parameter.proxyurl) ;
    var action = decodeURIComponent(e.parameter.action);
    try {
      switch (action) {
        case 'edit':
          content= JSON.stringify ({error: "action not yet implemented" + action}) ;
          break;
          //TODO return uiStuff (db, entry);
        case 'show':
          content = JSON.stringify(getMyStuff(entry,db));
          break;
        case 'oauth':
          content = oAuthProxy (db,entry, proxyurl).getContentText();
          break;
        default:
          content = JSON.stringify ({error: "unknown action - should be show or oauth" + action}) ;
          break;
      } 
    }
    catch (err) {
        content = JSON.stringify ( { error: err } );
    }
   }
   return content;
}
/**
 * oAuthPacket will create a packet of options and oauth parameters
 * @param {object} stuff contents of an oauth lockbox
 * @return {urlfetch.advancedoptions} the packet to use as options to urlfetch
 */ 
function oAuthPacket(stuff) {
  // relevant properties from silo
    var locker = stuff.result.myStuff;
    var siloId = stuff.result.siloId;
  // use GAS oauth library
    var oa = UrlFetchApp.addOAuthService(siloId);
    oa.setAccessTokenUrl (locker.accessUrl);
    oa.setRequestTokenUrl (locker.requestUrl);
    oa.setAuthorizationUrl(locker.authorizeUrl);
    oa.setConsumerKey(locker.consumerKey);
    oa.setConsumerSecret(locker.consumerSecret);
  // advanced oauth options
    return {
      "oAuthServiceName": siloId,
      "oAuthUseToken" : "always"
     };
}
/**
 * oAuthProxy will execute an oauth then call some url by proxy
 * @param {String} siloId siloid of the scriptdb locker holding the oauth information
 * @param {scriptDBInstance} db the private db to use
 * @param {String} url to execute
 * @return {String} response from the urlfetch
 */                
function oAuthProxy (db,siloId, url) {
  // get myStuff - this will have previously been stored in the myStuff locker
  var stuff = getMyStuff(siloId,db);
  DebugAssert(stuff.status.code == "good", "error getting secrets " + JSON.stringify(stuff) );
  // construct the oauth packet
  var packet = oAuthPacket(stuff);
  // issue request
   return UrlFetchApp.fetch(url, packet);
}
/**
 * return the stuff from the db associated with the e.parameter.entry value
 * @param {String} siloNamethe the locker name
 * @param {scriptdbinstance} db public db
 * @param {queryOb} optQuery optional query by example
 * @return {ContentService} the rest response
 */
function getPubStuff (siloName, db, optQuery) {
  var q;
  var response = {status: {code:"bad", reason:"unknown error"}, results:null};
  var ob = optQuery || {}; 
  q=  siloName ? scriptDbSilo(siloName,db).query(ob) : db.query(ob);
  if (q.hasNext()) {
    response.status.code = "good";
    response.status.reason = siloName + " found in your stuff";
    response.results =  [] ;
    while (q.hasNext()) {
      response.results.push(q.next());
    }
  }
  else {
    response.status.reason = siloName + " has no data";
    response.status.query = JSON.stringify(ob);
  }   
  return response;
}
/** react to a doGet(e) to return public data
 * @param {object} e as passed to doGet() 
 * @param {scriptdbinstance} db public db
 * @return {String} the json string content
 */
function getPubStuffContent (e,db) {
   //parameters 
   // e.parameter.entry - optional the lockBox entry name
  var content ;
  var entry =  e.parameter && e.parameter.entry ? decodeURIComponent(e.parameter.entry)  : null;
  try {
          content = JSON.stringify(getPubStuff(entry,db));
  } 
  catch (err) {
        content = JSON.stringify ( { error: err } );
  }
   return content;
}
/** show everything in a given db
 * @param {scriptdbinstance} db public db
 * @return {String} the json string content
 */
function showAll(db) {
  var results = db.query({});
  while (results.hasNext()) {
    var result = results.next();
    Logger.log(Utilities.jsonStringify(result));
  }
}

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