const delay = ms => {

return new Promise(r => setTimeout(() => r(), ms));

}

const url = "https://jsonplaceholder.typicode.com/todos";

// This is function with class promise.

function fetchByUrl() {

return delay(3000)

.then(() => fetch(url))

.then(response => response.json())

}

fetchByUrl()

.then(data => {

console.log(`Data from url: ${data}`);

})

.catch(error => console.error(error));

// This is function with async/await.

async function fetchByUrlAsync() {

try {

await delay(3000);

const response = await fetch(url);

const data = response.json();

console.log(`Data from url: ${data}`);

} catch (error) {

console.error(error);

} finally {

console.log("Finally.")

}

}

fetchByUrlAsync();