Disable the unicorn/no-array-reduce rule

[leroykorterink]

There is a proposal to disable the unicorn/no-array-reduce rule.

unicorn/no-array-reduce: super annoying. introduces unnecessary verbosity
- @edgardz

[leroykorterink]

Array#reduce() and Array#reduceRight() usually result in hard-to-read and less performant code. In almost every case, it can be replaced by .map, .filter, or a for-of loop.

It's only somewhat useful in the rare case of summing up numbers, which is allowed by default.
Use eslint-disable comment if you really need to use Array#reduce().

Please see the documentation of the rule.

[ThaNarie]

It would really be useful to have code examples where people really want to use reduce compared to suggested alternatives.

Then we can compare both variants and have a proper discussion.

[edgardz]

I use reduce all the time. It is a very powerful language feature we should not disable because some people are not familiar with it.
Here is an example I used it recently:

const x = 123

const children: HTMLElement[] = [...]

const closestChildIndex = children.reduce((previous, current, index) => {
  return Math.abs(current.offsetLeft + x) < Math.abs(children[previous].offsetLeft + x) ? index : previous
}, 0)

All the logic to achieve the closestChildIndex value is contained inside the reduce.

Otherwise I would have to do something like:

const x = 123

const children: HTMLElement[] = [...]

let closestChildIndex = 0
let closestChildOffset = Math.abs(children[0].offsetLeft + x)

for (let index = 1; index < children.length; index++) {
  const currentOffset = Math.abs(children[index].offsetLeft + x)
  if (currentOffset < closestChildOffset) {
    closestChildIndex = index
    closestChildOffset = currentOffset
  }
}

I don't know if I'm too familiar with how reduce works, but the first option is easier to read.

[ThaNarie]

I agree that that's a perfectly valid use case for reduce, and the best way to write it if you indeed need the index (and not the item).