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 Functions Arrow Functions Concise Arrow Function Syntax

Greg Radford
Greg Radford
7,126 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! 😄