Discussion on: The case for reducers

[Tiago Dias]

Hey, and first of all thanks for putting effort on your post. I hope it doesn't get lost in the flood of low quality ones...

Regarding your article I just want to point out that the first two examples, despite being doable with a .reduce(), in my opinion they're way complex. We can achieve the same by doing something like:

// Pretend these are complex objects
const posts = [
    { tags: ["javascript", "discuss"] },
    { tags: ["javascript", "react", "vue-is-better"] },
    { tags: ["discuss"] },
    { tags: ["javascript"] },
];

// const allTags = posts.map(post => post.tags).flat();
const allTags = posts.map(({ tags }) => tags).flat();
const allUniqueTags = new Set(allTags);

console.log(allUniqueTags); // Set(4) { 'javascript', 'discuss', 'react', 'vue-is-better' }

const posts = [
    { category: "javascript", tags: ["javascript", "discuss"] },
    { category: "frameworks", tags: ["javascript", "react", "vue-is-better"] },
    { category: "watercooler", tags: ["discuss"] },
    { category: "functional programming", tags: ["javascript"] },
];

// const capitalize = (word) => word[0].toUpperCase() + word.slice(1); 
const capitalize = ([initial, ...rest]) => initial.toUpperCase() + rest.join(''); 

// const discussable = posts.filter(post => post.tags.includes('discuss'));
const discussable = posts.filter(({ tags }) => tags.includes('discuss'));

// const capitalizedCategories = discussable.map(post => capitalize(post.category));
const capitalizedCategories = discussable.map(({ category }) => capitalize(category));

console.log(capitalizedCategories); // [ 'Javascript', 'Watercooler' ]

Regarding the pipe, that is the perfect use case for the reduce() !
Nice job explaining it.

I just wanted to bring more viable options to achieve the same outcome, not to undermine your examples.

Thanks once again!

[Heiker]

Thanks for the kind words.

---

About those examples I made in the post, interestingly enough they could also be done using Array.flatMap.

• Unique tags

new Set(posts.flatMap(({ tags }) => tags))

• FilterMap

posts.flatMap(({ tags, category }) =>
  tags.includes('discuss')
    ? capitalize(category)
    : []
);