Validation is an integral part of a web application. Making sure that a first validation pass is done on the client side can (to some extent) help you cleanse your data and show useful messages to your users when the input data is invalid. Angular comes with a pre-determined set of validators, and you can find find some validators libraries on GitHub, but sometimes this is not enough as you need custom rules for validating your data. Since form validation can occur through reactive forms or template driven forms, let’s go over each of them to see how we can add a custom validator in each case. Custom validator through reactive forms Validation can occur on a formControl or on a…