Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

JavaScript JavaScript Array Iteration Methods Array Manipulation Practice reduce()

victor E
victor E
19,145 Points
Posted by victor E
victor E
19,145 Points

Using reduce

Not sure what I am missing, i have a feeling it has something to do with scope

app.js 
const phoneNumbers = ["(503) 123-4567", "(646) 123-4567", "(503) 987-6543", "(503) 234-5678", "(212) 123-4567", "(416) 123-4567"];
let numberOf503;
numberOf503 = phoneNumbers.reduce((count, number) => {
    if(number[1] === '5') {
      return count + 1;
    }else return
}, 0);




// numberOf503 should be: 3
// Write your code below

1 Answer

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

There are no scope issues here. But when the count is not incremented, you still need to retain the count:

    } else return count;  // without "count" it returns "undefined"
victor E
victor E
19,145 Points
victor E
victor E
19,145 Points

That did the trick, thank you!