#JavaScript #Node.js

Gmail login in Node.js

To login to Gmail using Node.js, you can use the Gmail API which is provided by Google. Here’s a simple example:

1. First, you need to create a Google Cloud Platform project and enable the Gmail API. You can follow the instructions in the official Gmail API documentation: https://developers.google.com/gmail/api/quickstart/nodejs

2. Install the `google-auth-library` and `googleapis` modules using npm:

npm install google-auth-library googleapis

3. Once you have enabled the Gmail API and created the project, download the `credentials.json` file from the API Console.

4. Create a new file `gmail.js` and add the following code:

const fs = require('fs');
const readline = require('readline');
const { google } = require('googleapis');
const { OAuth2Client } = require('google-auth-library');

// Replace with the path to your credentials.json file
const CREDENTIALS_PATH = 'path/to/credentials.json';

// Replace with the path to your token.json file
const TOKEN_PATH = 'path/to/token.json';

// If modifying these scopes, delete the file token.json.
const SCOPES = ['https://www.googleapis.com/auth/gmail.readonly'];

// Load client secrets from a local file.
fs.readFile(CREDENTIALS_PATH, (err, content) => {
  if (err) return console.error('Error loading client secret file:', err);

  // Authorize a client with credentials, then call the Gmail API.
  authorize(JSON.parse(content), listLabels);
});

/**
 * Create an OAuth2 client with the given credentials.
 * @param {Object} credentials The authorization client credentials.
 */
function authorize(credentials, callback) {
  const { client_secret, client_id, redirect_uris } = credentials.installed;
  const oAuth2Client = new OAuth2Client(client_id, client_secret, redirect_uris[0]);

  // Check if we have previously stored a token.
  fs.readFile(TOKEN_PATH, (err, token) => {
    if (err) return getNewToken(oAuth2Client, callback);
    oAuth2Client.setCredentials(JSON.parse(token));
    callback(oAuth2Client);
  });
}

/**
 * Get and store new token after prompting for user authorization.
 * @param {Object} oAuth2Client The OAuth2 client to get token for.
 */
function getNewToken(oAuth2Client, callback) {
  const authUrl = oAuth2Client.generateAuthUrl({
    access_type: 'offline',
    scope: SCOPES,
  });
  console.log('Authorize this app by visiting this url:', authUrl);
  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
  });
  rl.question('Enter the code from that page here: ', (code) => {
    rl.close();
    oAuth2Client.getToken(code, (err, token) => {
      if (err) return console.error('Error retrieving access token', err);
      oAuth2Client.setCredentials(token);
      // Store the token to disk for later program executions
      fs.writeFile(TOKEN_PATH, JSON.stringify(token), (err) => {
        if (err) return console.error(err);
        console.log('Token stored to', TOKEN_PATH);
      });
      callback(oAuth2Client);
    });
  });
}

/**
 * Lists the labels in the user's account.
 * @param {google.auth.OAuth2} auth An authorized OAuth2 client.
 */
function listLabels(auth) {
  const gmail = google.gmail({ version: 'v1', auth });
  gmail.users.labels.list(
    {
      userId: 'me',
    },
    (err, res) =>