matching filename base

Question

Still learning regex here but I need a little help.

I have this string assets/BigBlueSomething_tn.jpg

I need to match this BigBlueSomething

Closest I got is this `[^\/][a-zA-Z]+_

Problem is that I keep matching the underscore I've tried this [^\/][a-zA-Z]+[^_] at the advice from several other threads but to no avail.

I'm writing in javascript, I believe there are some regex things that dont work in that language.

Answer 1

This should give you what you need:

var str = 'assets/BigBlueSomething_tn.jpg';
var match = str.split('/')[1].match(/[a-z]+/i)[0];

Edit: I used split because otherwise you'd have to loop the matches to extract what you need. match doesn't capture groups.

'assets/BigBlueSomething_tn.jpg'
       -^---------------------^- // .split('/')[1]
       -^--------------^- // .match(/[a-z]+/i)[0]

[a-z] // match any character from a to z
+ // at least one time
/i // case-insensitive to match A-Z as well

Answer 2

Try this:

var text = "assets/BigBlueSomething_tn.jpg";
var matches = /assets\/(.+?)_tn.jpg/gi.exec(text);
if(matches && matches[1]) {
    var str = matches[1];
}

Answer 3

/^(?:.*\/)?([0-9a-z]+)(?:_[a-z]+)?\.(?:jpg|jpeg|png|gif)$/i

This regex matches "BigBlueSomething" in the following strings:

'assets/BigBlueSomething_tn.jpg' 
'BigBlueSomething_tn.jpg'
'BigBlueSomething_TN.jPeG'
'dir1/dir2/BigBlueSomething_tn.gif'
'BigBlueSomething.png'
'BigBlueSomething_thumb.png'
'directory/BigBlueSomething_thumb.JPEG'

See this fiddle.