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Discussion on: You don't need Array.reduce()

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seniorjoinu profile image
Alexander • Edited

Seriously, man? for..of?

const myTotalLikes = retrieveAllPosts()
    .filter(p => p.user == me)
    .map(p => p.likes)
    .reduce((acc, like) => acc + like, 0)
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Sometimes it's better to use for..of (e.g. when you need some boost iterating over a huge collection you can do all the stuff in one loop) but functional style is much more useful when you are trying to express yourself to your colleagues.

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lewiscowles1986 profile image
Lewis Cowles

My head nearly exploded looking at that. Map reduce is not a good pattern for application engineering, it's a backend big-unstructured-data pattern.

retrievePostsFor(me) would be so much easier to think about as well. Baking in getting all posts and filtering is just not clear unless you have a shallow micro-service code-base, embrace the cascade.

Finally wrap that up in a method

function totalLikes(user) {
    return likes = retrievePostsFor(user)
        .map(p => p.likes)
        .reduce((sum, likes) => sum + likes, 0);
}
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lewiscowles1986 profile image
Lewis Cowles • Edited

to anyone liking this, it works better if you just send in users. Then it doesn't matter where they come from, and anything with 0 likes just adds items to the list...

In-fact it doesn't need to be a user at all. Just something implementing a likeable interface, which has a method to retrieve likes.