5_pitfalls.js

const fetch = require("node-fetch");
const url = "https://jsonplaceholder.typicode.com/posts/1";

function isStatus200(res) {
    console.log('Checking HTTP response status...');
    if (res.status === 200) {
        return res
    } else {
        let err = new Error(res.statusText);
        err.response = res;
        throw err;
    }
}

function getPostJson(res) {
    console.log('Getting JSON...');
    return res.json()
}

function getTitle(post) {
    console.log('Getting Title...');
    return post.title
}

function echoTitle(title) {
    console.log(title)
}


// Bad news - not returning, nesting, and not catching
// fetch(url).then(isStatus200)
//     .then(result => {
//         console.log('Got a result...');
//         getPostJson(result)
//             .then(post => getTitle(post));
//     }).then(title => echoTitle(title));

// Better news - terminate chain with catch, flatten
fetch(url)
    .then(isStatus200)
    .then(result => {
        console.log('Got a result...');
        return getPostJson(result)
    })
    .then(getTitle)
    .then(echoTitle)
    .catch(err => console.error(err));