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 Introducing ES2015 The Cooler Parts of ES2015 Default Parameters

Natalie Cluer
Natalie Cluer
18,898 Points
Posted by Natalie Cluer
Natalie Cluer
18,898 Points

undefined vs null?

Why do we pass in undefined as a parameter? what would the difference be between passing in undefined vs passing in null?

2 Answers

Stuart Wright
Stuart Wright
41,118 Points
Stuart Wright
Stuart Wright
41,118 Points

By using undefined, you are telling the function that you are choosing not to pass an argument in for name, so it knows to use the default value. By passing in null, you are telling it that you are passing in the value null as your name argument.

greet(undefined, 'Afternoon');

> Good Afternoon, Guil! 

greet(null, 'Afternoon');

> Good Afternoon, null!