JSFiddle - React, Tailwind, and code Playground
HTML
<div ng-app='app' ng-controller='myCtrl' ng-form='myForm'>
<input type='text' ng-model='ip' ng-pattern='/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/' placeholder='xxx.xxx.xxx.xxx' />
value : {{ ip }}
</div>
CSS
.ng-invalid { border: 1px solid red; }
JavaScript
var app = angular.module('app',[]).controller('myCtrl', function myCtrl ($scope) {
$scope.ip = ''
})