The simple library-constructor which validate form on the client side. Constructor is based on a "strategy" pattern and It can add your personal form check.
form-validation-constructor complemented browser's validation or replaced it with custom checks.
On the section how to add a custom check, you can see an example which add your own check to the list of checks.
You can install library with npm
npm install --save form-validation-constructorafter installation you can connect it to your project The best place to the connect is your root file, which combine all scripts example:
// connect to main scripts file
import formValidationConstructor from 'form-validation-constructor';
formValidationConstructor();