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JavaScript JavaScript Array Iteration Methods Combining Array Methods Combining filter() and reduce()

Why should I solve this way?

Hello, the task I need to solve sum of products over price 10.

I find my solution

const products = [
    { name: 'hard drive', price: 59.99 },
    { name: 'lighbulbs', price: 2.59 },
    { name: 'paper towels', price: 6.99 },
    { name: 'flatscreen monitor', price: 159.99 },
    { name: 'cable ties', price: 19.99 },
    { name: 'ballpoint pens', price: 4.49 },
];

const total = products
    .reduce((sum, product) => {
        if (product.price > 10) {
            return sum + product.price;
        }

        return sum;
    }, 0)
    .toFixed(2);

I think my solution is faster, but with filter is cleaner.

3 Answers

Tom Geraghty
Tom Geraghty
24,162 Points

Learning.

That's why.

Steven Parker
Steven Parker
220,425 Points

Contratulations, you re-invented "filter". :smirk: And yes, it is a bit faster.

But if you were going purely for efficiency, a good ol' "for" loop would be even better:

let sum = 0;
for (let i = 0; i < products.length; i++) {
        if (products[i].price > 10) sum += products[i].price;
}
const total = sum.toFixed(2);

But the purpose of the exercise was not to write the fastest code, but to practice the use of these array methods.

I was looking for best practices. It doesn't mean you can do it, you should do it.

Steven Parker
Steven Parker
220,425 Points

I don't think the choice of method falls into the "best practices" category. Both ways do the job and the code is easy to read and maintain.