promisify javascript code example

Example 1: promisify

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

const stat = util.promisify(fs.stat);
stat('.').then((stats) => {
  // Do something with `stats`
}).catch((error) => {
  // Handle the error.
});

Example 2: js promisify in browser

function promisify(func, callbackPos) {
  return (...args) => {
    return new Promise((resolve) => {
      const cb = (...args) => {
        resolve(args);
      };
      args.splice(callbackPos ? callbackPos : args.length, 0, cb);
      func(...args);
    });
  };
};