Sometimes, we want to replace callbacks with promises in Node.js.

In this article, we’ll look at how to replace callbacks with promises in Node.js.

How to replace callbacks with promises in Node.js?

To replace callbacks with promises in Node.js, we can use the util.promisify method.

For instance, we write

import mysql from 'mysql';
const util = require('util');

const connection = mysql.createConnection({
  host: 'localhost',
  user: 'user',
  password: 'password',
  database: 'db'
});

const connectAsync = util.promisify(connection.connectAsync);
const queryAsync = util.promisify(connection.queryAsync);

const getUsersAsync = async () => {
  await connectAsync()
  return queryAsync('SELECT * FROM Users')
};

to convert the connection.connectAsync and connection.queryAstnc methods to functions that returns promises with util.promisify.

Then in the getUsersAsync function, we call them both.

We use await to wait for the promise returned by connectAsync to resolve before calling queryAsync.

Conclusion

To replace callbacks with promises in Node.js, we can use the util.promisify method.