JavaScript

Promises

const fetchData = user => {
  setTimeout(() => {
    console.log(`Data fetched for ${user}`);
  }, 3000);
};

const onFetchSuccess = () => {
  console.log("Data fetched successfully");
};

fetchData("John");
onFetchSuccess();


const fetchData = (user, callback) => {
  setTimeout(() => {
    console.log(`Data fetched for ${user}`);
    callback();
  }, 3000);
};

const onFetchSuccess = () => {
  console.log("Data fetched successfully");
};

fetchData("John", onFetchSuccess);
