Async JavaScript

Normal functions in JS

The way to write functions in JS is as follows -

Find sum of two numbers

function sum(a, b) {
	return a + b;
}

let ans = sum(2, 3)
console.log(sum);

Find sum from 1 to a number

function sum(n) {
	let ans = 0;
	for (let i = 1; i <= n; i++) {
		ans = ans + i
	}
	return ans;
}

const ans = sum(100);
console.log(ans);

Synchronous code

Synchronous code is executed line by line, in the order it's written. Each operation waits for the previous one to complete before moving on to the next one.

For example

function sum(n) {
	let ans = 0;
	for (let i = 1; i <= n; i++) {
		ans = ans + i
	}
	return ans;
}

const ans1 = sum(100);
console.log(ans1);
const ans2 = sum(1000);
console.log(ans2);
const ans3 = sum(10000);
console.log(ans3);

I/O heavy operations

I/O (Input/Output) heavy operations refer to tasks in a computer program that involve a lot of data transfer between the program and external systems or devices. These operations usually require waiting for data to be read from or written to sources like disks, networks, databases, or other external devices, which can be time-consuming compared to in-memory computations.

Examples of I/O Heavy Operations:

Reading a file
Starting a clock
HTTP Requests