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 Pass Information Into Functions Variable Scope

Stephen Cole
PLUS
Stephen Cole
Courses Plus Student 15,809 Points
Posted by Stephen Cole
Stephen Cole
Courses Plus Student 15,809 Points

Does creating a parameter define the scope of a variable?

If I create a function with a parameter, does that force the scope to be local?

let person = 'Lee';

function greeting(person) {
  person = 'Meg';
  alert(`Hi, ${person};
}

A quick test shows that it is local and does NOT change the global variable. However, is that really what is happening or is there other magic behind the scenes?

1 Answer

Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

Giving a parameter or new function variable the same name as a variable in the outer scope makes it not possible to access the outer variable. This is known as "shadowing".

If this isn't desired, the only reliable remedy is to give the variables and parameters unique names.