regex - HTML5 pattern for IP address - how to modify pattern to ignore the "_" (underscore) character -

i have found following pattern validating syntax of ip address:

 pattern="((^|\.)((25[0-5])|(2[0-4]\d)|(1\d\d)|([1-9]?\d))){4}$" 

but need modify ignore _ characters in places. because use input mask (it removes _ after defocusing field bootstrap validator plugin sometime doesn't catch it).

so how can modify regex ignore _ characters?

example strings should valid:

 192.168.88.1__    192.168.88_.200  192.16_.88_.2__  192.168.88.2 

in order match optional characters (0 or more occurrences), need * quantifier. so, match ip addresses _ after numbers, can add _* after each number:

((^|\.)((25[0-5]_*)|(2[0-4]\d_*)|(1\d\d_*)|([1-9]?\d_*))){4}_*$ 

see demo

although, think can remove anchors safely since html5 pattern attribute anchored default. can change regex match ip more intelligently (without allowing dot before it):

(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)_*(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)_*){3} 

see another demo