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

About reduce() and filter()

I have a question again, I dont know how this work. But it seems really close to success, just dont know why where is the error.

Hope someone can help me out,thank you so much!

app.js
const purchaseItems = [
    {
        name: 'apples',
        dept: 'groceries',
        price: 2.49
    },
    {
        name: 'bread',
        dept: 'groceries',
        price: 2.99
    },
    {
        name: 'batteries',
        dept: 'electronics',
        price: 5.80
    },
    {
        name: 'eggs',
        dept: 'groceries',
        price: 3.99
    },
    {
        name: 't-shirts',
        dept: 'apparel',
        price: 9.99
    }
];
let groceryTotal;

// groceryTotal should be: 9.47
// Write your code below
groceryTotal = purchaseItems.filter(fi=>{fi.dept == 'groceries'})
                            .reduce((acc,ui) => acc+ui.price,0);

1 Answer

Steven Parker
Steven Parker
229,788 Points

You're really close, but an arrow function that has a body in braces needs an explicit "return" statement to pass back a value. Here you can use the abbreviated form which returns implicitly:

/*...*/ .filter(fi => fi.dept == 'groceries')

Oh, I dont know still. So, within the arrow function the difference between curly braces and without curly braces is return and no return value, right?

Thank you so much!

Steven Parker
Steven Parker
229,788 Points

Yes, one statement with no braces is automatically returned. But a function body in braces must call "return" explicitly.

Thank you so much!