Discussion on: Stop using for loops. Here's why.

[Jordy Lee]

... And it's articles like this that make me think we were better off before anyone could publish anything on the internet.

The main problem I have is your piece is actually well written, thus it is probably going to be taken as gospel by newbie devs.
I enjoy the ease of writing callback functions instead of for loops as much as anyone, but it is such a biased outlook to claim that this is always the right solution.

Why don't you mention the areas where imperative loops outshine higher order functions? E.g. the fact that a for loop is ~10x faster than a forEach callback

[Jack Shen]

E.g. the fact that a for loop is ~10x faster than a forEach callback

I believe this is untrue. Can you substantiate this claim?

[Jordy Lee]

It's widely known that loops based on callback functions generally perform much worse than imperative loops. Here's an example, where forEach is 96% slower than a vanilla for loop: stackoverflow.com/questions/438217...

C'mon man, I appreciate that you want to share your knowledge, but if you are going to write posts with such provocative titles then you need to know this stuff. I am a big fan of functional programming and much prefer it over OOP, but the aspect I dislike most about FP is the performance hit from making everything immutable

[matgott]

Try yourself.

let arr = [];
for(x = 0; x < 100000; x++) {arr.push(Math.random());}

function oldFor(d) {
aux = [];
const t0 = performance.now();
for(x=0; x < d.length; x++) {
aux.push(d);
}
return (performance.now() - t0);
}

function eachFor(d) {
let aux = [];
const t0 = performance.now();
d.forEach(v => {
aux.push(v);
});
return (performance.now() - t0);
}

oldFor(arr);
eachFor(arr);

[joey542]

Okay. This is your code in typescript with a 10M length array. The forEach time is double.

I made another for just testing the other loops with a 10M length array.

So... the conclusion is... If you want to loop through big arrays just use the old for loop. And I made an account just for to send this comment.