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

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Replies for: for loops either mutate data or perform side effects, which as a general rule why they are good to avoid. map, filter, and reduce also allow bette...

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crazy4groovy profile image
crazy4groovy •

I think you mean

const add = (a, b) => a + b
const sum = array.reduce(add, 0)

You need a seed value.

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joelnet profile image
JavaScript Joel •

Nope. That is exactly what I meant.

The seed is optional. If you don't provide a seed, the first item in the array is given as the accumulator.

Run the code!

const add = (a, b) => a + b

[1, 2, 3].reduce(add) //=> 6
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fregante profile image
Fregante • • Edited

Sum is just about the only case where reduce is useful, but in reality it should never be passed around like that. Why keep an add function around that is only meant to be used together with a reduce? Just wrap it once and never use reduce again:

const sum = (array) => array.reduce((a, b) => a + b);

sum([1, 2, 3]) //=> 6
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Don't tell me arr.reduce(add) makes more sense than sum(arr) because it doesn't.

In reality you can write sum event more efficiently with a regular loop and every part of your code benefits.