This is a Node.js module that exports a function named mailer.
The function relies on several packages:
path: a built-in Node.js package that allows the module to resolve file paths.nodemailer: a package that enables email functionality.nodemailer-express-handlebars: a package that allows for the use of Handlebars templates within emails.
The mailer function takes in several parameters:
from: the email address of the sender.to: the email address of the recipient.template: the name of the Handlebars template that should be used when constructing the email.data: an object containing the context data that should be used when rendering the Handlebars template.user: the username for the email account from which the email should be sent.pass: the password for the email account from which the email should be sent.
The mailer function creates a nodemailer Transport object using the gmail service and the provided user and pass. It then uses the nodemailer-express-handlebars package to configure the Transport object to use Handlebars templates.
The function constructs a mailOptions object that contains information about the email, including the sender, recipient, subject, and the Handlebars template and context data that should be used. Finally, it calls the sendMail method on the Transport object with the mailOptions object as a parameter. If the email is successfully sent, it logs a message indicating this. If there is an error sending the email, it logs an error message.