I kind of hate people who use the JavaScript array method Array.reduce(...)
It rarely makes sense but makes code unnecessarily complex to read.

What do you use when you want to summate something or fill a dictionary from an array?

I've have to look up the differences between map reduce and filter way way way too often.

@N00bPancakes Filter filters and reduce reduces. What is complicated about it?

@N00bPancakes
Just mentally replace the word reduce with fold. It folds the result of an n-value series into a single resulting value. It folds a series of value together.

Filter just returns an array that is all values from the source array where the predicate returned true.

@lamka02sk

I think it is more of a semantic satiation thing.

I use map, filter, every day. Less so reduce.

But then I type out another one and ... it just occurs to me I'm in zombie mode, the method syntax is similar, I start wonder about the vastness of the universe, and maybe not entirely sure what the difference is between them ;)

@SortOfTested Your mentioned usecase is one of the few where reduce is appropriate.
I see it abused wher a map, find, filter or loop would have been the right choice.

@PonySlaystation
Had to check, lots of readability trolls on the internet who don't like declarative programming in any context ;)

Appropriateness does indeed matter. Usually, if you're side effecting, you should avoid the declarative method. Though I personally thing you should avoid side effecting in pretty much every case.

@N00bPancakes
Got bored in a pointless sales meeting, so I wrote up an example primer-as-code on it, with some other goodies thrown in.

https://stackblitz.com/edit/...

It's useful, and maybe the only possible one-liner for finding sum of an array, It might be difficult to read, but if you are using JS, understanding it is a better option than not using it.

@SortOfTested Thanks! I think I'll have to unpack some of the RxJS and Observable to figure this out entirely ;)

Oh hey, array methods!

https://codepen.io/AmyShackles/...

@AmyShackles 😎

@N00bPancakes
The reason I like that approach is because of how broken the JS declarative array fns are.

Each function will produce an entirely new array buffer for each operation. This results in a significiantly greater space complexity than you would usually expect from a streamlike interface.

Rx will apply every operator to each value before the next value is processed, so the space complexity is always 1n.