validation's Introduction

Enhancements

First class TypeScript support
Asynchronous validation
Entity validation
Multiple controllers per view.
Drop validate.js
Errors that aren't specific to a particular property/element
Conditional validation
Make it easier to define custom rules
Make it easier to customize error messages / I18N
Keyed message resources
Use binding engine to render message templates
Improve renderer API to make animation scenarios and "success" scenarios possible

Under Consideration

Enable specifying rules for nested properties: ValidationRules.ensure('foo.bar.baz').required();
Validation sequencing: add an option or change the standard behavior such that rules specific to a particular property are validated sequentially. The first validation error cancels the remaining validation work for the property. Side-effect: properties would never have more than one error. Benefit: expensive rules could be validated only when everything else is valid.

& validate does not work with two-way custom attributes because it's unable to locate the associated DOM element.
Rule property decorators missing. @required, etc

Fluent API: ensure, displayName Rules: required, satisfies, min/max-length/items, email, matches Message customization: withMessage, withMessageKey when,
Replacing default messages