promise-intro.js

const fs = require('fs');
const {promisify} = require('util');
// Using Node 8.x to create a promise for us
let asyncReadFile = promisify(fs.readFile);

/**
Create your own Promise
**/
function readFile(fileName){
    return new Promise(function(accept, reject){
        fs.readFile(fileName, "utf-8", function(err, result){
            if(err){
                return reject(err);
            }
            return accept(result);
        })
    });
}

(async () => {

    let result = await  readFile("cale.txt"); //asyncReadFile("cale.txt", "utf-8")
    console.log(result);
    
})();