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()

Posted by saddam lashuel
saddam lashuel
Courses Plus Student 9,178 Points

JavaScript Array Iteration methods

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((acc, num)=>{ if(num.slice(1,4)== 503){ return acc + 1; }
},0);

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((acc, num)=>{
          if(num.slice(1,4)== 503){
              return acc + 1; }          
},0);

1 Answer

Steven Parker
Steven Parker
231,184 Points
Steven Parker
Steven Parker
231,184 Points

The callback function should still return something even if current number doesn't add to the count.

saddam lashuel
saddam lashuel
Courses Plus Student 9,178 Points

Thanks!!!!