Polymer sugars Web Components standards with awesome features for creating custom elements:
Declarative custom element definition.
Define custom elements declaratively using
Markup and style encapsulation.
Shadow DOM encapsulates your element's internals.
Template markup is compartmentalized, and styles don't leak in or out.
Published properties.
Properties that are published can be initialized via markup and invoke change handlers when modified.
Declarative data binding.
Properties on the element can be bound directly into the view, with robust support for expressions.
Declarative event binding.
Event handlers can be bound to functions on the element declaratively using on-event attributes.
Declarative event binding.
Event handlers can be bound to functions on the element declaratively using on-event attributes.