Google Sheets App Script- Add signature when sending e-mail - email

Question

I'm working on a script that will save my Google Sheet spreadsheet as a pdf and email it as an attachment. The code I'm using works, but I don't know how to add a signature to the email I'm sending. Is this possible, and if so; what would be the cleanest way to do it? Here's the code I'm working with. I know, it's not pretty.
function displayPrompt() {
var ss=SpreadsheetApp.getActiveSpreadsheet();
var sheetName = ss.getActiveSheet().getName();
var ui = SpreadsheetApp.getUi();
var result = ui.prompt("Please enter email body");
//Get the button that the user pressed.
var button = result.getSelectedButton();
var message = {
to: "someone#somewhere.com",
subject: sheetName,
body: "Hi team,\n\nPlease find attached the quote that you requested.\n" +
result.getResponseText() + "\nThank you,\nMe",
name: "My Name",
attachments:
[SpreadsheetApp.getActiveSpreadsheet().getAs(MimeType.PDF).setName("Quote")]
}
if (button === ui.Button.OK) {
Logger.log("The user clicked the [OK] button.");
Logger.log(result.getResponseText());
MailApp.sendEmail(message);
} else if (button === ui.Button.CLOSE) {
Logger.log("The user clicked the [Cancel] button.");
}
}

Answer 1

I believe your goal as follows.
You want to add the signature to the message of Gmail using MailApp.sendEmail
In this case, I think that there are 2 patterns.
Pattern 1:
In this pattern, by declaring the signature as the variable, the signature is added.
Sample script:
Please modify message in your script as follows.
var signature = "\nsample signature"; // Added
var message = {
to: "someone#somewhere.com",
subject: sheetName,
body: "Hi team,\n\nPlease find attached the quote that you requested.\n" + result.getResponseText() + "\nThank you,\nMe" + signature, // Modified
name: "My Name",
attachments: [SpreadsheetApp.getActiveSpreadsheet().getAs(MimeType.PDF).setName("Quote")]
}
Pattern 2:
In this pattern, by retrieving the sigunature of Gmail, the signature is added.
Sample script:
In this sample, Gmail API is used. So, before you use this script, please enable Gmail API at Advanced Google services. And, please modify message in your script as follows.
var signature = "<br>" + Gmail.Users.Settings.SendAs.list("me").sendAs[0].signature; // Added
var message = {
to: "someone#somewhere.com",
subject: sheetName,
htmlBody: ("Hi team,\n\nPlease find attached the quote that you requested.\n" + result.getResponseText() + "\nThank you,\nMe").replace(/\n/g, "<br>") + signature, // Added
name: "My Name",
attachments: [SpreadsheetApp.getActiveSpreadsheet().getAs(MimeType.PDF).setName("Quote")]
}
The signature retrieved from Gmail is HTML. So in this pattern, htmlBody is used instead of body.
References:
Method: users.settings.sendAs.list