Callbacks X Promissified

fetching-data-by-wrapping-the-callback-in-a-promise.js

const http = require('http')

const baseApiUrl = 'http://jsonplaceholder.typicode.com'

// using error-back pattern --> or anti-pattern :)
const fetchDataWithPromise = () => {
    return new Promise((resolve, reject) => {

        http.get(`${baseApiUrl}/posts`, res => {
            let rawData = '';
            res.on('data', chunk => rawData += chunk)
            res.on('end', () => {
                const data = JSON.parse(rawData);
                // when things are done, we resolve the promise
                resolve(data)
            })
            res.on('error', err => {
                console.log('----- ERR -----\n', err.message)
                // if things went south we can reject the promise
                reject(err)
            })
        }).end()
    })
}

const main = async () => {
    try {
        const data = await fetchDataWithPromise()
        console.log(data)
    } catch (err) {
        console.log(err)
    }
}

main()

fetching-data-with-callbacks.js

const http = require('http')

const baseApiUrl = 'http://jsonplaceholder.typicode.com'

// using error-back pattern --> or anti-pattern :)
const fetchDataWithCallback = (callback) => {
    http.get(`${baseApiUrl}/posts`, res => {
        let rawData = '';
        res.on('data', chunk => rawData += chunk)
        res.on('end', () => {
            const data = JSON.parse(rawData);
            // when things are done, we execute the callback function
            callback(null, data)
        })
        res.on('error', err => {
            console.log('----- ERR -----\n', err.message)
            callback(err, null)
        })
    }).end()
}

const main = async () => {
    const printDataAfterFetching = (err, data) => {
        if (!err) {
            console.log(data)
        } else {
            console.log(err)
        }
    }
    fetchDataWithCallback(printDataAfterFetching)
}

main()