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 trialHamzah Iqbal
Full Stack JavaScript Techdegree Student 11,145 PointsThis reduce method should work, but why isn't it?
```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((sum, phoneNumber) => {
if(phoneNumber.substring(2,4) === "503") {
return phoneNumbers +1;
} return phoneNumbers;
},0); // numberOf503 should be: 3 // Write your code below
console.log(numberOf503);
Right now it is returning the last in the array, but I can't see why. The substring should return the specified digits.
```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((sum, phoneNumber) => {
if(phoneNumber.substring(2,4) === "503") {
return phoneNumbers +1;
}
return phoneNumbers;
},0);
// numberOf503 should be: 3
// Write your code below
console.log(numberOf503);
1 Answer
Steven Parker
231,269 PointsIt looks like there are two issues:
- string indexes begin at zero, and the substring stop value should be the value after the last index
- the function should return the total (sum) instead of the array itself (phoneNumbers)
numberOf503 = phoneNumbers.reduce((sum, phoneNumber) => {
if (phoneNumber.substring(1,4) === "503") {
return sum + 1;
}
return sum;
}, 0);