Polymer
By Google
Polymer was a JavaScript library from Google for building web applications using standards-based Web Components, letting developers create reusable, encapsulated custom HTML elements.
Definition
Polymer was a JavaScript library from Google for building web applications using standards-based Web Components, letting developers create reusable, encapsulated custom HTML elements.
Overview
Google introduced Polymer in 2015 to make the then-emerging Web Components specifications (Custom Elements, Shadow DOM, HTML templates) practical to use, at a time when browser support for those standards was inconsistent. Polymer provided polyfills and a convenient authoring layer for defining custom elements with data binding, so developers could build UI as a set of reusable `<my-element>` tags rather than framework-specific components. Google used Polymer internally for products in that era and released a companion library of Material Design elements, which made it a visible reference implementation of the Web Components approach as an alternative to component models tied to a specific framework like React or Angular. As native browser support for Web Components matured, Google shifted its investment toward Lit (originally lit-html/LitElement), a smaller successor library that keeps the standards-based philosophy but drops much of Polymer's polyfill weight and legacy API surface. Polymer itself is now in maintenance/legacy status, with Lit serving as its effective successor for teams that want standards-based custom elements today.
Key Features
- Standards-based approach built directly on Web Components specifications
- Custom element definitions with declarative data binding
- Shadow DOM encapsulation for style and markup isolation
- Polyfills for browsers lacking native Web Components support
- Companion Material Design element library
- One-way and two-way data binding between element properties and templates