Form validation
The application provides various ways to validate your form inputs. This implementation is based, and extends, jQuery Validation.
Validation module structure
There are three main validation modules: jquery/validate, mage/validation, and mage/validation/validation.
jquery/validate
This is an alias for lib/web/jquery/jquery.validate. This is the base validation JavaScript file provided by jQuery that the application extends.
mage/validation
This module is present at lib/web/mage/validation.js. This module includes jquery/validate and adds various functions, such as $.validator.addMethod, which can be used by mixins to add custom validation rules, a base set of rules to validate, the mage.validation widget, and more.
mage/validation/validation
This module is present at lib/web/mage/validation/validation.js. This is considered the entry point for the form validator and is aliased as validation at Magento_Theme/view/frontend/requirejs-config.js. This includes mage/validation (which in turn includes jquery/validate), and adds a few more rules to the validator.
