Asynchronous in JavaScript

🔴 Synchronous (Normal)

One task mudinja apram thaan next task start aagum.

console.log("One");
console.log("Two");
console.log("Three");

👉 Output:

One
Two
Three

🟢 Asynchronous

Long task background-la nadakkum,
short task immediate-aa execute aagum.

console.log("Start");

setTimeout(() => {
console.log("Middle");
}, 2000);

console.log("End");

👉 Output:

Start
End
Middle

🔹 Why Asynchronous needed?

API call time edukkum

File loading time edukkum

Timer, user input wait

👉 App freeze aagama irukka asynchronous use pannrom.

🔹 Common Asynchronous methods
1️⃣ setTimeout()

Delay ku apram run aagum

setTimeout(() => {
console.log("Hello");
}, 1000);

2️⃣ setInterval()

Repeated-aa run aagum

setInterval(() => {
console.log("Hi");
}, 2000);

3️⃣ Promise

Future-la result varum nu promise

let promise = new Promise((resolve, reject) => {
resolve("Success");
});

4️⃣ async / await

Promise-a simple-aa handle panna

async function loadData() {
let result = await fetch(url);
}