Regex to extract the username from a string

Question

I have a string name that can include the following possiblities and I wish to use a regex expression to remove that X part of the string with its corresponding underscore and obtain the filename only.

Possibilities of string name :

1. XXX_XXX_filename
2. XXX_filename

kindly note that X is an uppercase and consists of alphabets {AZ} only. Can i have a regex that removes the X parts with the underscore as well?

Answer 1

You can repeat 1 or 2 times matching 1 or more uppercase chars [AZ] followed by an underscore.

In the replacement use an empty string.

(?:[A-Z]+_){1,2}

Regex demo

Answer 2

You can try this:

"XXX_XXX_filename".replace(/^[A-Z_]*/g,"")

If you know the number of total characters you can restrict the regexp a bit more:

"XXX_XXX_filename".replace(/^[A-Z_]{3,7}/g,"")

If you also know the total number of groups for upper case you could use this alos:

"XXX_XXX_Filename".replace(/^([AZ]+_?){0,2}/g,"")