Regex expression for matching snake case

I’m trying to build a Regex expression for matching just snake case strings. I’m not really good at Regex. What I’ve built is:

([a-zA-Z]+)_([a-zA-Z]+)

But this isn’t quite good because it doesn’t match all the cases. I want to be able to add more words, not just 2, and also, I want to match just letters and the underscore. I mention that I’ll use this with Javascript.

Do you have some better options, please? 🙂 Thanks!

>Solution :

[a-zA-Z]+(_[a-zA-Z]+)*

should work fine

Version with non-capturing groups:

[a-zA-Z]+(?:_[a-zA-Z]+)*