Blog · Callbacks

Callbacks in JavaScript

A callback is a function passed as an argument to another function and is executed after the completion of a task.

function fetchData(callback) {
  setTimeout(() => {
    console.log('1. fetching data');
    callback();
  }, 5000);
}

function processData() {
  console.log('2. processing data');
}

fetchData(processData);
/*
  After 5 sec
  ===========
    1. fetching data
    2. processing data
*/