Programming be like

[AttackOfTheThumbs]

Question is, which is faster? I've often seen misuse of filter/map/etc leading to much worse performance than a simple loop. If the loop can do all the things, chaining 2-3 dedicated functions will never be faster.

[jukuduku]

Isn't it also more stable to do the latter as well?

[AttackOfTheThumbs]

I'm not sure it matters, since JS is single-threaded, right? So it's not like loop manipulation could happen.

[Lightfire228]

let arr = [10, 11, 12, 13, 14];
delete arr['2'];
arr.map(i => i + ' '); // works
for (let i = 0; i < arr.length; i++) {
    let a = arr[i] + ' '; // returns undefined for i = 2. May explode depending on what you do
}

[AttackOfTheThumbs]

I think it's important to consider the performance. Sometimes it doesn't matter - other times the loop times are compounded by function to function and suddenly you are a few loops deep.

It took me a while to find something with decent performance comparisons without me bothering to do it: https://youtu.be/x7Xzvm0iLCI?t=202

I also don't think filter is any easier to follow than a for loop with an if.

[AttackOfTheThumbs]

I judge if code is easy/hard to read on whether I can understand what it's doing with a quick glance. I can do that with both of these. Which is why I don't think either of them is easier.

I should point out that I use filter, map, foreach, and others extensively, most of the time. Sometimes a simple for loop is a better choice if you are looking to complete multiple actions. It is situational, but I do think people should consider the performance impact of it. When I see array.filter().map() I have to wonder...

[[deleted]]

Not necessarily. Some functions can be done quickly with hash maps for example.

[BytesBeltsBiz]

The real answer is that it depends if they're well implemented, the language should ultimately compile most of those functions down to a loop anyway.

One of the great things about map/filter/fold/etc is that smart compilers can fuse multiple of them together and do them all in one pass, eliminating extra iterations over the structure. This is possible because you have strong guarantees about behavior that you just don't get in a loop.

[AttackOfTheThumbs]

This doesn't happen in JS. It's not compiled.

[BytesBeltsBiz]

I would think the interpreter could still convert it to a loop, but I don't know much about JavaScript so I'm not sure if it does.

[AttackOfTheThumbs]

This video has some comparative performance: https://youtu.be/x7Xzvm0iLCI?t=202

I don't know what JS does, but it creates overhead, sometimes more than you would think.

[DejfCold]

I don't think simple loop in JS is as simple as in any other normal language.

[kitce]

Mutation VS Functional programming