Promisify - Javascript

Promisify is a utility in Javascript that converts callback-style functions into Promises. This enables the usage of Promise-based programming patterns, which is in tune with ES6 standards.

For example, suppose you have a function in Node.js that reads a file using a callback function:

const fs = require('fs');

fs.readFile('/path/to/file', (err, data) => {
  if (err) {
    console.error(err);
  } else {
    console.log(data);
  }
});

Using Promisify, you can convert this function into one that returns a Promise:

const util = require('util');
const fs = require('fs');

const readFile = util.promisify(fs.readFile);

readFile('/path/to/file')
  .then(data => console.log(data))
  .catch(err => console.error(err));

As you can see, promisify() takes a function that has a callback as its last argument, and returns a new function that returns a Promise. The new function takes the same arguments as the original function, except that the last one is now optional as it is replaced by then and catch methods.

Promisify is particularly useful for controlling the flow of asynchronous programming. It provides a clean and consistent way of dealing with asynchronous operations in a manner that is easy to understand and debug.

Overall, Promisify is a useful tool for Javascript programmers, making it possible to write tidy and efficient code that is both easy to read and maintain.