diff --git a/mashups/sheets2calendar.gs b/mashups/sheets2calendar.gs
index b878b1f1f..5461cb4ab 100644
--- a/mashups/sheets2calendar.gs
+++ b/mashups/sheets2calendar.gs
@@ -6,37 +6,38 @@
  */
 function createEventsFromSpreadsheet() {
   // Open the spreadsheet and get the data.
-  var ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
-  var sheet = ss.getSheets()[0];
-  var data = sheet.getDataRange().getValues();
+  const ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
+  const sheet = ss.getSheets()[0];
+  /** @type {string[][]} */
+  const data = sheet.getDataRange().getValues();
 
   // Remove any frozen rows from the data, since they contain headers.
   data.splice(sheet.getFrozenRows());
 
   // Create an event for each row.
   data.forEach(function(row) {
-    var title = row[0];
-    var description = row[1];
-    var emails = row[2];
+    const title = row[0];
+    const description = row[1];
+    const emailsStr = row[2];
 
     // Split the emails into an array and remove extra whitespace.
-    emails = emails.split(',').map(function(email) {
+    const emails = emailsStr.split(',').map(function(email) {
       return email.trim();
     });
 
-    var now = new Date();
+    const now = new Date();
     // Start the event at the next hour mark.
-    var start = new Date(now);
+    const start = new Date(now);
     start.setHours(start.getHours() + 1);
     start.setMinutes(0);
     start.setSeconds(0);
     start.setMilliseconds(0);
     // End the event after 30 minutes.
-    var end = new Date(start);
+    const end = new Date(start);
     end.setMinutes(end.getMinutes() + 30);
 
     // Create the calendar event and invite the guests.
-    var event = CalendarApp.createEvent(title, start, end)
+    const event = CalendarApp.createEvent(title, start, end)
         .setDescription(description);
     emails.forEach(function(email) {
       event.addGuest(email);
diff --git a/mashups/sheets2chat.gs b/mashups/sheets2chat.gs
index bf888b3ea..81ee9fe77 100644
--- a/mashups/sheets2chat.gs
+++ b/mashups/sheets2chat.gs
@@ -1,3 +1,9 @@
+/**
+ * @typedef {Object} SheetEditEvent
+ * @property {string} oldValue The old value of the cell.
+ * @property {string} value The new value of the cell.
+ */
+
 /**
  * Posts a message to a Hangouts Chat room every time the spreadsheet is edited.
  * This script must be attached to the spreadsheet (created in Google Sheets under
@@ -8,16 +14,16 @@
  *   "From spreadsheet", "On edit".
  * - Click "Save".
  *
- * @param {Object} e The onEdit event object.
+ * @param {SheetEditEvent} e The onEdit event object.
  */
 function sendChatMessageOnEdit(e) {
-  var range = SpreadsheetApp.getActiveRange();
-  var value = range.getValue();
-  var oldValue = e.oldValue;
-  var ss = range.getSheet().getParent();
+  const range = SpreadsheetApp.getActiveRange();
+  const value = range.getValue();
+  const oldValue = e.oldValue;
+  const ss = range.getSheet().getParent();
 
   // Construct the message to send, based on the old and new value of the cell.
-  var changeMessage;
+  let changeMessage;
   if (oldValue && value) {
     changeMessage = Utilities.formatString('changed from "%s" to "%s"',
         oldValue, value);
@@ -26,17 +32,17 @@ function sendChatMessageOnEdit(e) {
   } else {
     changeMessage = 'cleared';
   }
-  var message = Utilities.formatString(
+  const message = Utilities.formatString(
       'The range %s was %s. <%s|Open spreadsheet>.',
       range.getA1Notation(), changeMessage, ss.getUrl());
 
   // Follow these steps to create an incomming webhook URL for your chat room:
   // https://developers.google.com/hangouts/chat/how-tos/webhooks#define_an_incoming_webhook
-  var webhookUrl = 'ENTER INCOMMING WEBHOOK URL HERE';
+  const webhookUrl = 'ENTER INCOMMING WEBHOOK URL HERE';
 
   // Use the spreadsheet's ID as a thread key, so that all messages go into the
   // same thread.
-  var url = webhookUrl + '&threadKey=' + ss.getId();
+  const url = webhookUrl + '&threadKey=' + ss.getId();
 
   // Send the message.
   UrlFetchApp.fetch(url, {
diff --git a/mashups/sheets2contacts.gs b/mashups/sheets2contacts.gs
index 0eb90452c..746034396 100644
--- a/mashups/sheets2contacts.gs
+++ b/mashups/sheets2contacts.gs
@@ -5,18 +5,18 @@
  */
 function createContactsFromSpreadsheet() {
   // Open the spreadsheet and get the data.
-  var ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
-  var sheet = ss.getSheets()[0];
-  var data = sheet.getDataRange().getValues();
+  const ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
+  const sheet = ss.getSheets()[0];
+  const data = sheet.getDataRange().getValues();
 
   // Remove any frozen rows from the data, since they contain headers.
   data.splice(sheet.getFrozenRows());
 
   // Send a contact for each row.
   data.forEach(function(row) {
-    var firstName = row[0];
-    var lastName = row[1];
-    var email = row[2];
+    const firstName = row[0];
+    const lastName = row[1];
+    const email = row[2];
     ContactsApp.createContact(firstName, lastName, email);
   });
 }
diff --git a/mashups/sheets2docs.gs b/mashups/sheets2docs.gs
index 1ee48553f..7b0c78c61 100644
--- a/mashups/sheets2docs.gs
+++ b/mashups/sheets2docs.gs
@@ -6,26 +6,27 @@
  */
 function createDocsFromSpreadsheet() {
   // Open the spreadsheet and get the data.
-  var ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
-  var sheet = ss.getSheets()[0];
-  var data = sheet.getDataRange().getValues();
+  const ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
+  const sheet = ss.getSheets()[0];
+  /** @type {string[][]} */
+  const data = sheet.getDataRange().getValues();
 
   // Remove any frozen rows from the data, since they contain headers.
   data.splice(sheet.getFrozenRows());
 
   // Create a document for each row.
   data.forEach(function(row) {
-    var title = row[0];
-    var content = row[1];
-    var emails = row[2];
+    const title = row[0];
+    const content = row[1];
+    const emailsStr = row[2];
 
     // Split the emails into an array and remove extra whitespace.
-    emails = emails.split(',').map(function(email) {
+    const emails = emailsStr.split(',').map(function(email) {
       return email.trim();
     });
 
     // Create the document, append the content, and share it out.
-    var doc = DocumentApp.create(title);
+    const doc = DocumentApp.create(title);
     doc.getBody().appendParagraph(content);
     doc.addEditors(emails);
   });
diff --git a/mashups/sheets2drive.gs b/mashups/sheets2drive.gs
index 61145921d..8d869f0b9 100644
--- a/mashups/sheets2drive.gs
+++ b/mashups/sheets2drive.gs
@@ -6,30 +6,31 @@
  */
 function createDriveFilesFromSpreadsheet() {
   // Open the spreadsheet and get the data.
-  var ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
-  var sheet = ss.getSheets()[0];
-  var data = sheet.getDataRange().getValues();
+  const ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
+  const sheet = ss.getSheets()[0];
+  /** @type {string[][]} */
+  const data = sheet.getDataRange().getValues();
 
   // Remove any frozen rows from the data, since they contain headers.
   data.splice(sheet.getFrozenRows());
 
   // Create a PDF in Google Drive for each row.
   data.forEach(function(row) {
-    var fileName = row[0];
-    var htmlContent = row[1];
-    var emails = row[2];
+    const fileName = row[0];
+    const htmlContent = row[1];
+    const emailsStr = row[2];
 
     // Split the emails into an array and remove extra whitespace.
-    emails = emails.split(',').map(function(email) {
+    const emails = emailsStr.split(',').map(function(email) {
       return email.trim();
     });
 
     // Convert the HTML content to PDF.
-    var html = Utilities.newBlob(htmlContent, 'text/html');
-    var pdf = html.getAs('application/pdf');
+    const html = Utilities.newBlob(htmlContent, 'text/html');
+    const pdf = html.getAs('application/pdf');
 
     // Create the Drive file and share it out.
-    var file = DriveApp.createFile(pdf).setName(fileName);
+    const file = DriveApp.createFile(pdf).setName(fileName);
     file.addEditors(emails);
   });
 }
diff --git a/mashups/sheets2forms.gs b/mashups/sheets2forms.gs
index 0fec56774..fe14a8536 100644
--- a/mashups/sheets2forms.gs
+++ b/mashups/sheets2forms.gs
@@ -6,26 +6,27 @@
  */
 function createFormsFromSpreadsheet() {
   // Open the spreadsheet and get the data.
-  var ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
-  var sheet = ss.getSheets()[0];
-  var data = sheet.getDataRange().getValues();
+  const ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
+  const sheet = ss.getSheets()[0];
+  /** @type {string[][]} */
+  const data = sheet.getDataRange().getValues();
 
   // Remove any frozen rows from the data, since they contain headers.
   data.splice(sheet.getFrozenRows());
 
   // Create a form for each row.
   data.forEach(function(row) {
-    var title = row[0];
-    var question = row[1];
-    var emails = row[2];
+    const title = row[0];
+    const question = row[1];
+    const emailsStr = row[2];
 
     // Split the emails into an array and remove extra whitespace.
-    emails = emails.split(',').map(function(email) {
+    const emails = emailsStr.split(',').map(function(email) {
       return email.trim();
     });
 
     // Create the form, append the question, and share it out.
-    var form = FormApp.create(title);
+    const form = FormApp.create(title);
     form.addTextItem().setTitle(question);
     form.addEditors(emails);
   });
diff --git a/mashups/sheets2gmail.gs b/mashups/sheets2gmail.gs
index 3a0c6ee6d..7d5ed23ff 100644
--- a/mashups/sheets2gmail.gs
+++ b/mashups/sheets2gmail.gs
@@ -6,21 +6,22 @@
  */
 function sendEmailsFromSpreadsheet() {
   // Open the spreadsheet and get the data.
-  var ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
-  var sheet = ss.getSheets()[0];
-  var data = sheet.getDataRange().getValues();
+  const ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
+  const sheet = ss.getSheets()[0];
+  /** @type {string[][]} */
+  const data = sheet.getDataRange().getValues();
 
   // Remove any frozen rows from the data, since they contain headers.
   data.splice(sheet.getFrozenRows());
 
   // Send an email for each row.
   data.forEach(function(row) {
-    var subject = row[0];
-    var htmlMessage = row[1];
-    var emails = row[2];
+    const subject = row[0];
+    const htmlMessage = row[1];
+    const emails = row[2];
 
     // Send the email.
-    GmailApp.sendEmail(emails, subject, null, {
+    GmailApp.sendEmail(emails, subject, '', {
       htmlBody: htmlMessage
     });
   });
diff --git a/mashups/sheets2maps.gs b/mashups/sheets2maps.gs
index 97c592b61..33e4d29c6 100644
--- a/mashups/sheets2maps.gs
+++ b/mashups/sheets2maps.gs
@@ -12,11 +12,13 @@
  * @customFunction
  */
 function COUNTY(address) {
-  var results = Maps.newGeocoder().geocode(address).results;
+  const results = Maps.newGeocoder().geocode(address).results;
   if (!results || results.length === 0) {
     throw new Error('Unknown address');
   }
-  var counties = results[0].address_components.filter(function(component) {
+  /** @type {{long_name: string, types: string[]}[]} */
+  const addressComponents = results[0].address_components;
+  const counties = addressComponents.filter(function(component) {
     return component.types.indexOf('administrative_area_level_2') >= 0;
   });
   if (!counties.length) {
diff --git a/mashups/sheets2slides.gs b/mashups/sheets2slides.gs
index 551ab76b3..6a140911a 100644
--- a/mashups/sheets2slides.gs
+++ b/mashups/sheets2slides.gs
@@ -6,29 +6,30 @@
  */
 function createPresentationsFromSpreadsheet() {
   // Open the spreadsheet and get the data.
-  var ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
-  var sheet = ss.getSheets()[0];
-  var data = sheet.getDataRange().getValues();
+  const ss = SpreadsheetApp.openByUrl('ENTER SPREADSHEET URL HERE');
+  const sheet = ss.getSheets()[0];
+  /** @type {string[][]} */
+  const data = sheet.getDataRange().getValues();
 
   // Remove any frozen rows from the data, since they contain headers.
   data.splice(sheet.getFrozenRows());
 
   // Create a presentation for each row.
   data.forEach(function(row) {
-    var title = row[0];
-    var content = row[1];
-    var emails = row[2];
+    const title = row[0];
+    const content = row[1];
+    const emailsStr = row[2];
 
     // Split the emails into an array and remove extra whitespace.
-    emails = emails.split(',').map(function(email) {
+    const emails = emailsStr.split(',').map(function(email) {
       return email.trim();
     });
 
     // Create the presentation, insert a new slide at the start, append the content,
     // and share it out.
-    var presentation = SlidesApp.create(title);
-    var slide = presentation.insertSlide(0, SlidesApp.PredefinedLayout.MAIN_POINT);
-    var textBox = slide.getShapes()[0];
+    const presentation = SlidesApp.create(title);
+    const slide = presentation.insertSlide(0, SlidesApp.PredefinedLayout.MAIN_POINT);
+    const textBox = slide.getShapes()[0];
     textBox.getText().appendParagraph(content);
     presentation.addEditors(emails);
   });
diff --git a/mashups/sheets2translate.gs b/mashups/sheets2translate.gs
index 06b38c492..a863e8378 100644
--- a/mashups/sheets2translate.gs
+++ b/mashups/sheets2translate.gs
@@ -9,10 +9,10 @@
  * under "Tools > Script editor").
  */
 function onEdit() {
-  var range = SpreadsheetApp.getActiveRange();
-  var value = range.getValue();
+  const range = SpreadsheetApp.getActiveRange();
+  const value = range.getValue();
   if (typeof value === 'string') {
-    var translated = LanguageApp.translate(value, null, 'en');
+    const translated = LanguageApp.translate(value, '', 'en');
     range.setNote(translated);
   }
 }