Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

JavaScript JavaScript Functions Arrow Functions Concise Arrow Function Syntax

Greg Radford
Greg Radford
5,180 Points

Omitting the return keyword in an arrow function

In the "Arrow Functions as One-line Statements", you say you can omit the return keyword, but this doesnt seem correct as it returns undefined.

It seems you both have to omit the return keyword AND the curly brackets?

This will run:

const getRandomNumber = x => { return x * x };

This will return undefined:

const getRandomNumber = x => { x * x };

This will run:

const getRandomNumber = x => x * x ;

1 Answer

Rohald van Merode
seal-mask
STAFF
.a{fill-rule:evenodd;}techdegree
Rohald van Merode
Treehouse Staff

Hey Greg Radford 👋

You are right! For a one liner you can omit both the return keyword as well as the curly braces. If you have a multiline block of code to run you can use parentheses instead of curly brackets which would also be implicitly returned.

const getRandomNumber = x => (
    x * x 
);

Thanks again for bringing this to our attention, I've rewarded you with the Exterminator badge for reporting this bug and will be updating the instructions shortly! 😄