4 ms·

How would you abuse reduce()?

Too 3y ago
MDN even had to make a whole chapter to discourage overuse of it. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce#when_to_not_use_reduce https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...
masklinn 3y ago
Using reduce to perform a map is a fun way to annoy colleagues.
- 5e92cb50239222b 3y ago
  Or .map() as a for..of replacement. I always wanted V8/SpiderMonkey developers to make .map()/.reduce() "pure" in the sense of "optimizing away" the expression if its result is not assigned to anything, and see the world burn.
  - Zababa 3y ago
    I think .map() as a for...of replacement makes sense for simple cases. newArray = oldArray.map(el => aFunction(el)) is short, sweet and clean.
    - orra 3y ago
      It's definitely short, but are you doing it for the side effects? Then I find .map() misleading. I'd much prefer a .forEach(), or a for...of.
      - masklinn 3y ago
        If you’re mapping for side effects you deserve a good rap on the head. The main value of “map” is to denote a 1:1 data transformation. Plus this gets very fraught with many langages mapping lazily, and some not guaranteeing the order of operation.
pwdisswordfishc 3y ago
Use it at all, presumably.
- JuanPosadas 3y ago
  I'm probably on the mild side of abusing it, I've never seen another developer on my team use it, but I also include self-describing variables for the values. If the reducer function itself is non-trivial, I've give it a name so the final product may look like: const idNameMap = itemList.reduce(toIdNameMap) It should be intuitive that itemList is a list of objects familiar to the context of the code, and the result will be like: [{"id1":"Billy"}, etc.
  - masklinn 3y ago
    It’s really not clear to me what the transformation is, but from the naming and result it mostly looks like it’s an abuse of reduce and should be a map, possibly feeding into an Object / Map constructor / factory?
  - yakshaving_jgt 3y ago
    > It should be intuitive that itemList is a list of objects …But how?! I can't see how anyone could build an intuition for this opaque line and the example of its apparent result. It's confusing enough that `idNameMap` actually refers to a list (or array), and not a map (or object).

Too 3y ago

MDN even had to make a whole chapter to discourage overuse of it. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce#when_to_not_use_reduce https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

masklinn 3y ago

Using reduce to perform a map is a fun way to annoy colleagues.

5e92cb50239222b 3y ago
Or .map() as a for..of replacement. I always wanted V8/SpiderMonkey developers to make .map()/.reduce() "pure" in the sense of "optimizing away" the expression if its result is not assigned to anything, and see the world burn.
- Zababa 3y ago
  I think .map() as a for...of replacement makes sense for simple cases. newArray = oldArray.map(el => aFunction(el)) is short, sweet and clean.
  - orra 3y ago
    It's definitely short, but are you doing it for the side effects? Then I find .map() misleading. I'd much prefer a .forEach(), or a for...of.
    - masklinn 3y ago
      If you’re mapping for side effects you deserve a good rap on the head. The main value of “map” is to denote a 1:1 data transformation. Plus this gets very fraught with many langages mapping lazily, and some not guaranteeing the order of operation.

pwdisswordfishc 3y ago

Use it at all, presumably.

JuanPosadas 3y ago
I'm probably on the mild side of abusing it, I've never seen another developer on my team use it, but I also include self-describing variables for the values. If the reducer function itself is non-trivial, I've give it a name so the final product may look like: const idNameMap = itemList.reduce(toIdNameMap) It should be intuitive that itemList is a list of objects familiar to the context of the code, and the result will be like: [{"id1":"Billy"}, etc.
- masklinn 3y ago
  It’s really not clear to me what the transformation is, but from the naming and result it mostly looks like it’s an abuse of reduce and should be a map, possibly feeding into an Object / Map constructor / factory?
- yakshaving_jgt 3y ago
  > It should be intuitive that itemList is a list of objects …But how?! I can't see how anyone could build an intuition for this opaque line and the example of its apparent result. It's confusing enough that `idNameMap` actually refers to a list (or array), and not a map (or object).