chaining-promises.js

function getTodos(resource) {
            return new Promise((resolve, reject) => {
                const request = new XMLHttpRequest();

                request.addEventListener("readystatechange", () => {
                    if (request.readyState === 4 && request.status === 200) {
                        resolve(request.responseText);
                    } else if (request.readyState === 4) {
                        reject("Error getting resource");
                    }
                });

                request.open("GET", resource);
                request.send();
            });
        }

getTodos("https://jsonplaceholder.typicode.com/todos/").then((data) => {
    console.log(JSON.parse(data)[0]);
    return getTodos('https://jsonplaceholder.typicode.com/users/');
}).then(data => {
    console.log(JSON.parse(data)[0])
    return getTodos('https://jsonplaceholder.typicode.com/posts/');
}).then(data => {
    console.log(JSON.parse(data)[0]);
}).catch(err => {
    console.log(err)
});