正则表达式 (Javascript) 用于解析带有 firstname.lastname.randomnumber@email.com 的电子邮件

Question

I've scoured all the other threads about this but there's a unique aspect to my parsing format that I can't get past. I'm trying to parse an email address with a standard format as follows - firstname.lastname.#####@email.com ie 'john.smith.12345@email.com'

I want to return any alpha characters before the numeric sequence - 'john smith' (or all names before the .12345 in case people have multiple names).

Right now, I've worked out the regex to (^[A-Za-z]+\\.+[A-Za-z]+) but that returns 'john.smith' which isn't the end of the world since I can split it.

Any help would be much appreciated.

Answer 1

Click on the code blocks below to try them out.

If you only have two or three dot-separated names before the numbers, you can hardcode the group alternatives:

(?:([A-Za-z]+)\\.([A-Za-z]+)|([A-Za-z]+)\\.([A-Za-z]+)\\.([A-Za-z]+))\\.\\d+@[^\\s@]+

Here we use a non-capturing group to enclose the alternatives.

For one, two, or three dot-separated names, the pattern is similar (albeit a bit messier).

---

Another approach would be to wrap some of the preceding dot + capturing group sections with an optional non-capturing group.

([A-Za-z]+)\\.([A-Za-z]+)(?:\\.([A-Za-z]+))?\\.\\d+@[^\\s@]+

This enables a more concise expression of 1-3 dot-separated names as:

([A-Za-z]+)(?:\\.([A-Za-z]+))?(?:\\.([A-Za-z]+))?\\.\\d+@[^\\s@]+