"As you all know that JavaScript is synchronous, using console or any callback or promise/fetch will make the function asynchronous." Using console doesn't make the function asynchronous. It may likely make it technically impure though (although it doesn't affect the idempotency of the function either, so that's debatable). To be clear, a function that calls another function can still be a pure function.

Hm, what happens with multi-line logs?

Hi Skay, thanks for the article. There is an incorrect comment in your code: //Higher order function - takes 'func' as an argument & returns a 'func' for execution const higherOrderFunction = function(func, a, b) { return func(a, b); } This function is not actually returning a function, but rather the result of the callback function, which is data. A more concise example might be: const sum = function(a, b) { return a + b; } //Higher order function - takes 'func' as an argument & returns a 'func' for execution const higherOrderFunction = (func) => (a, b) => { return func(a, b); } const sumFor = higherOrderFunction(sum); console.log(sumFor(2,3)); Here, higherOrderFunction takes func and returns a function, which then takes a,b and return data. Cheers!