Promisify Core Api

this is a node module who will inject new Async methods im core module of NodeJS based on Sync function with usage of callback method promisify by util.promisify(callback)

For example, in NodeJS we have in fs :

• fs.readFileSync(path) : string (bad idea)
• fs.readFile(path, callback: (err, content :str) => void) : void (good but risk of callback hell)

With require this module you'll have a new function :

• fs.readFileAsync(path) : Promise<content: string, err> (Yeah a Promise, we can chain, await, etc..., help to keep a flat code ^^)

Requirements

no-one except Node 8+

The big magic is in the new util.promisify function added in Node 8.

Install

npm install promisify-core-api --save

Usage

In the earlier entry point of your program :

require('promisify-core-api');

And thats it, now, everywhere on your program, you can replace a Sync Node Core function by Async and use use the Promise returned.

Example

With Promise style

require('promisify-core-api'); // at the very earlier entry point of your program, One time

// somewhere in your code
const path = require('path');
const fs = require('fs');

// then
fs.readFileAsync(path.join(__filename))
  .then(txt => console.log(txt.toString()))
  .catch(err => console.log(err));

// catch
fs.readFileAsync(path.join(__dirname, __dirname))
  .then(txt => console.log(txt.toString()))
  .catch(err => console.log(err));

With async - await style

require('promisify-core-api'); // at the very earlier entry point of your program, One time

// somewhere in your code
const path = require('path');
const fs = require('fs');

// async IIFE, yeah it's preaty ugly but we can't await in global scope, global scope is not async
(async () => {
    // then
    try {
        const txt = await fs.readFileAsync(path.join(__filename));
        console.log(txt.toString());
    } catch (err) {
        console.log(err);
    }

    // catch
    try {
        const txt = await fs.readFileAsync(path.join(__dirname, __dirname));
        console.log(txt.toString());
    } catch (err) {
        console.log(err);
    }
})();

Bonus

const functions = require('promisify-core-api');

console.log(functions);

You will see all supported functions, and get original sync, callback api and the promisify api (function name, not directly the function).

See below part of this big object

{
    'require(\'fs\')': [
        {
            sync: 'accessSync',
            promise: 'accessAsync',
            callback: 'access'
        },
        {
            sync: 'existsSync',
            promise: 'existsAsync',
            callback: 'exists'
        },
        {
            sync: 'readFileSync',
            promise: 'readFileAsync',
            callback: 'readFile'
        },
        {
            sync: 'closeSync',
            promise: 'closeAsync',
            callback: 'close'
        },
        {
            sync: 'openSync',
            promise: 'openAsync',
            callback: 'open'
        },
        {
            sync: 'readSync',
            promise: 'readAsync',
            callback: 'read'
        },
        {
            sync: 'writeSync',
            promise: 'writeAsync', 
            callback: 'write'
        },
        {
            sync: 'renameSync',
            promise: 'renameAsync',
            callback: 'rename'
        }, ...
    ], ...
}