cb-topromise-wrapper

Description

Easily turn a function that takes a callback to instead returning a promise.

Requirements

The callback must be the last parameter and have node style parameters.

function cb(error, result){
    if(error){
        // handle error
    } else{
        // handle result
    }
}

Usage

$ npm install -S cb-topromise-wrapper

// var promiseWrapper = require(cb-topromise-wrapper).promiseWrapper;
import { promiseWrapper } from 'cb-topromise-wrapper';
const fs = require('fs');

const readFile = promiseWrapper(fs.readFile);
readFile('JsonData/yourfile.json', 'utf8')
    .then(console.log.bind(console))
    .catch(console.error.bind(console));

If you like node style result.

// var promiseWrapper = require(cb-topromise-wrapper).promiseWrapper;
import { promiseWrapper } from 'cb-topromise-wrapper';
const fs = require('fs');

function resultHandler({error, result}){
    if(error){
        // handle error
    } else{
        // handle result
    }
}
const readFile = promiseWrapper(fs.readFile);
readFile('JsonData/yourfile.json', 'utf8')
    .then(result => resultHandler({error: null, result}))
    .catch(error => resultHandler({error, result: null}));

Gotcha

If you wants to wrap a method you must replace it or bind it.

If the method is in the prototype and you want's every new instance to have the wrapped method you must remember to replace the prototype method.

You can also bind the method to the object.

// var promiseWrapper = require(cb-topromise-wrapper).promiseWrapper;
import { promiseWrapper } from 'cb-topromise-wrapper';
import { createBlobService } from 'azure-storage';

const blobService = createBlobService();

const createBlockBlobFromText = promiseWrapper(blobService.createBlockBlobFromText.bind(blobService));