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 Combining Array Methods Nested Data and Additional Exploration

Begana Choi
PLUS
Begana Choi
Courses Plus Student 13,126 Points
Posted by Begana Choi
Begana Choi
Courses Plus Student 13,126 Points

why concat doesn't work with {}?

const flatMovies = movies.reduce((arr,movie)=> {arr.concat(movie)},[]);

why this code doesn't work but without {} is working?

1 Answer

Steven Parker
Steven Parker
231,236 Points
Steven Parker
Steven Parker
231,236 Points

In the full arrow function syntax, where you have a code body in braces, nothing is returned unless you include an explicit "return" statement.

But in the abbreviated syntax, where you have only a single expression and no braces, the result of the expression is automatically returned.