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 Regular Expressions in JavaScript Validating a Form Validating an Email

Begana Choi
Begana Choi
Courses Plus Student 13,126 Points

why do we use case insensitive for /^[^@]+@[^@.]+\.[a-z]+$/i.test(email); ?

I think I don't understand exactly about case insensitive. I need some more examples to understand it except the examples on video!

1 Answer

Steven Parker
Steven Parker
229,607 Points

Since email addresses can contain upper and/or lower case, using case insensitivity makes it simpler to construct a pattern. For example, by itself, "[a-z]" would only match lower-case. So "us" would pass, but "US" would not. Making it case-insensitive allows both to pass.

Of course, you could also explicitly specify the pattern as "[A-Za-z]", but that's more verbose.