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JavaScript Regular Expressions in JavaScript Validating a Form Validating a Username

Daniel Grigo
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Daniel Grigo
Full Stack JavaScript Techdegree Graduate 18,815 Points
Posted by Daniel Grigo
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Daniel Grigo
Full Stack JavaScript Techdegree Graduate 18,815 Points

Why does /^[a-z]+$/ work?

I'm missing the explanation why this expression works. To me, a string like aadFKjh should also be valid considering this regex because it starts and ends with lowercase letters. So how does it work?

1 Answer

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

This regex accepts a variable length string composed entirely of lower-case letters. Every letter must match the character class defined by "[a-z]". Any upper-case letter, not just at the start or end, would not match and therefore the entire string would be rejected.