@lit-labs/ssr-dom-shim

Overview

This package provides minimal implementations of Element, HTMLElement, EventTarget, Event, CustomEvent, CustomElementRegistry, and customElements, designed to be used when Server Side Rendering (SSR) web components from Node, including Lit components.

Usage

Usage from Lit

Lit itself automatically imports these shims when running in Node, so Lit users should typically not need to directly depend on or import from this package.

See the lit.dev SSR docs for general information about server-side rendering with Lit.

Usage in other contexts

Other libraries or frameworks who wish to support SSR are welcome to also depend on these shims. (This package is planned to eventually move to @webcomponents/ssr-dom-shim to better reflect this use case). There are two main patterns for providing access to these shims to users:

1. Assigning shims to globalThis, ensuring that assignment occurs before user-code runs.

2. Importing shims directly from the module that provides your base class, using the node export condition to ensure this only happens when running in Node, and not in the browser.

Lit takes approach #2 for all of the shims except for customElements, Event and CustomEvent, so that users who have imported lit are able to call customElements.define or new Event(...)/new CustomEvent(...) in their components from Node.

Exports

The main module exports the following values. Note that no globals are set by this module.

• EventTarget
  • addEventListener
  • dispatchEvent
  • removeEventListener
• Element
  • (Inherits from EventTarget)
  • attachShadow
  • shadowRoot
  • attributes
  • hasAttribute
  • getAttribute
  • setAttribute
  • removeAttribute
• HTMLElement
  • (Inherits from Element)
• CustomElementRegistry
• customElements
• Event
• CustomEvent

Contributing

Please see CONTRIBUTING.md.