Skip to content

Instantly share code, notes, and snippets.

@tobymurray

tobymurray/sendEmail.js

Last active Feb 29, 2020
Embed
What would you like to do?
Send email with Gmail and NodeJS
const fs = require('fs');
const readline = require('readline');
const google = require('googleapis');
const googleAuth = require('google-auth-library');
const Base64 = require('js-base64').Base64;
const SCOPES = ['https://mail.google.com/',
'https://www.googleapis.com/auth/gmail.modify',
'https://www.googleapis.com/auth/gmail.compose',
'https://www.googleapis.com/auth/gmail.send'
];
const TOKEN_DIR = (process.env.HOME || process.env.HOMEPATH ||
process.env.USERPROFILE) + '/.credentials/';
const TOKEN_PATH = TOKEN_DIR + 'gmail-nodejs-quickstart.json';
/**
* Read the contents of the client secret JSON file
*
* @param {String} filename - name of the file containing the client secrets
*/
function readClientSecret(filename) {
return new Promise((resolve, reject) => {
fs.readFile(filename, (err, content) => {
if (err) {
return reject('Error loading client secret from ' + filename +
' due to ' + err);
}
return resolve(content);
});
});
}
/**
* Create an OAuth2 client with the given credentials
*
* @param {Object} credentials The authorization client credentials.
*/
function authorize(credentials) {
let clientSecret = credentials.installed.client_secret;
let clientId = credentials.installed.client_id;
let redirectUrl = credentials.installed.redirect_uris[0];
let auth = new googleAuth();
let oauth2Client = new auth.OAuth2(clientId, clientSecret, redirectUrl);
return new Promise((resolve, reject) => {
// Try reading the existing token
fs.readFile(TOKEN_PATH, function (err, token) {
if (err) {
// If there isn't an existing token, get a new one
resolve(getNewToken(oauth2Client));
} else {
oauth2Client.credentials = JSON.parse(token);
resolve(oauth2Client);
}
});
});
}
/**
* Get and store new token after prompting for user authorization, then return
* authorized OAuth2 client.
*
* @param {google.auth.OAuth2} oauth2Client The OAuth2 client to get token for.
*/
function getNewToken(oauth2Client) {
let authUrl = oauth2Client.generateAuthUrl({
access_type: 'offline',
scope: SCOPES
});
console.log('Authorize this app by visiting this url: ', authUrl);
let readlineInterface = readline.createInterface({
input: process.stdin,
output: process.stdout
});
return new Promise((resolve, reject) => {
readlineInterface.question('Enter the code from that page here: ',
(code) => {
readlineInterface.close();
oauth2Client.getToken(code, (err, token) => {
if (err) {
return reject('Error while trying to retrieve access token', err);
}
oauth2Client.credentials = token;
storeToken(token);
return resolve(oauth2Client);
});
});
});
}
/**
* Store token to disk be used in later program executions.
*
* @param {Object} token The token to store to disk.
*/
function storeToken(token) {
try {
fs.mkdirSync(TOKEN_DIR);
} catch (err) {
if (err.code != 'EEXIST') {
throw err;
}
}
fs.writeFile(TOKEN_PATH, JSON.stringify(token));
console.log('Token stored to ' + TOKEN_PATH);
}
/**
* Build an email as an RFC 5322 formatted, Base64 encoded string
*
* @param {String} to email address of the receiver
* @param {String} from email address of the sender
* @param {String} subject email subject
* @param {String} message body of the email message
*/
function createEmail(to, from, subject, message) {
let email = ["Content-Type: text/plain; charset=\"UTF-8\"\n",
"MIME-Version: 1.0\n",
"Content-Transfer-Encoding: 7bit\n",
"to: ", to, "\n",
"from: ", from, "\n",
"subject: ", subject, "\n\n",
message
].join('');
return Base64.encodeURI(email);
}
/**
* Send Message.
*
* @param {String} userId User's email address. The special value 'me'
* can be used to indicate the authenticated user.
* @param {String} email RFC 5322 formatted, Base64 encoded string.
* @param {google.auth.OAuth2} oauth2Client The authorized OAuth2 client
*/
function sendMessage(email, oauth2Client) {
let request = google.oauth2("v2").google.gmail('v1').users.messages.send({
auth: oauth2Client,
userId: 'me',
'resource': {
'raw': email
}
});
}
// Do everything!
let to = 'receiver@gmail.com';
let from = 'sender@gmail.com';
let subject = 'Subject the email generated with NodeJS';
let message = 'Big long email body that has lots of interesting content';
readClientSecret('client_secret.json')
.then(clientSecretJson => {
let clientSecret = JSON.parse(clientSecretJson);
return authorize(clientSecret);
}).then(oauth2client => {
let email = createEmail(to, from, subject, message);
sendMessage(email, oauth2client);
}).catch(error => {
console.error(error);
});
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.