Comment by Zhe Wang on "JavaScript Patterns — Wrangling arrays like a boss, with Array#reduce 👊" | Hashnode

Zhe Wang

#2's reducer functions needs to return acc because acc.push returns the pushed item:

const squaresOfNumbers = numArray => numbers.reduce(
    (acc, item) => {
       acc.push(item * item);
        return acc;
    },
    []
);

Sai Kishore Komanduri

Engineering an eGovernance Product | Hashnode Alumnus | I love pixel art

push returns the length of the array after the push operation; but, yea, we need to return acc. Thanks for pointing it out! Fixed it! :)

David Chase

Lead Software Developer

Why not just use concat instead of push ? make its nice and compact and easy to follow along:

const squaresOfNumbers = numArray => numArray.reduce((acc, item) => acc.concat(item * item), [])

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