Update Date or Send Email when a Specific Range is Edited - google-apps-script

Question

How do I tell cell C2 to set the date when cells A2 or B2 have been updated?
Further, how do I trigger the sending of my email function when A2 or B2 have been updated?
My issue is that onEdit fires anytime the document is edited at all, but I only want an action if a specific range is edited.
For the sending of emails, I've found and edited a script that almost works, but it sends me email notifications whenever any cell in the document is changed rather than just when column G is changed. Any suggestions?
function sendNotification() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getActiveSheet();
var cell = ss.getActiveCell().getA1Notation();
var row = sheet.getActiveRange().getRow();
var cellvalue = ss.getActiveCell().getValue().toString();
var recipients = "me#email.com";
var message = 'Cell value has been changed';
if(cell.indexOf('G')!=-1){
message = sheet.getRange('D'+ sheet.getActiveCell().getRowIndex()).getValue()
}
var subject = 'Update to '+sheet.getName();
var body = sheet.getName() + ' has been updated. Visit ' + ss.getUrl() + ' to view the changes on row: «' + row + '». New comment: «' + cellvalue + '». For message: «' + message + '»';
MailApp.sendEmail(recipients, subject, body);
};
Does this have to do with my onEdit() function being off?
For anyone that needs the final scripts
I ended up splitting this up in two separate functions. Here are the finished scripts.
The first one is the email notifications
/* This function send an email when a specified range is edited
* The spreadsheets triggers must be set to onEdit for the function
*/
function sendNotification() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getActiveSheet();
//Get Active cell
var mycell = ss.getActiveSelection();
var cellcol = mycell.getColumn();
var cellrow = mycell.getRow();
//Define Notification Details
var recipients = ENTEREMAILHERE;
var subject = "Update to "+ss.getName();
var body = ss.getName() + "has been updated. Visit " + ss.getUrl() + " to view the changes.";
//Check to see if column is A or B to trigger
if (cellcol == EDITMECOLUMN)
{
//check for row to trigger
if (cellrow == EDITMEROW)
{
//Send the Email
MailApp.sendEmail(recipients, subject, body);
}
//End sendNotification
}
}
And here is the one for time stamps
/* This function saves the date in a cell
* every time a specific row or column is edited
* The spreadsheets triggers must be set to onEdit for the function
*/
function setDate() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getActiveSheet();
//Get Active cell
var mycell = ss.getActiveSelection();
var cellcol = mycell.getColumn();
var cellrow = mycell.getRow();
//Check to see if column is A or B to trigger
if (cellcol == EDITMECOLUMN)
{
//check for row to trigger
if (cellrow == EDITMEROW)
{
//Find cell and set date in a defined cell
var celldate = sheet.getRange(EDITMEROW, EDITMECOLUMN);
celldate.setValue(new Date());
//end set date
}
}
}

Answer 1

This should work or at least give you the idea as I do something very similar. I usually set the trigger for this to be onEdit()
function sendNotification() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getActiveSheet();
//Get Active cell
var mycell = ss.getActiveSelection();
var cellcol = mycell.getColumn();
var cellrow = mycell.getRow();
//Check to see if column is A or B to trigger email
if (cellcol == 1 || cellcol ==2)
{
//check for row to trigger email
if (cellrow ==2)
{
//Find cell and set date
var celldate = sheet.getRange(2, 3);
celldate.setValue(new Date());
//end set date
var cellvalue = mycell.getValue().toString();
var recipients = "me#email.com";
var message = 'Cell value has been changed';
if(cell.indexOf('G')!=-1){
message = sheet.getRange('D'+ sheet.getActiveCell().getRowIndex()).getValue()
}
var subject = 'Update to '+sheet.getName();
var body = sheet.getName() + ' has been updated. Visit ' + ss.getUrl() + ' to view the changes on row: «' + row + '». New comment: «' + cellvalue + '». For message: «' + message + '»';
MailApp.sendEmail(recipients, subject, body);
}
}
}

Answer 2

Your onEdit(event) needs to check the event.range and make decisions based on that.
See Understanding Events.
Here's an answer to a similar question.