custom-element

Overview

The Problem

Extending a JS class from Rust/Wasm is not currently supported by wasm-bindgen: https://github.com/rustwasm/wasm-bindgen/issues/210, https://github.com/rustwasm/wasm-bindgen/issues/210. This functionality, however is essential for creating a custom element on the web, since custom elements must inherit from HTMLElement (or some other valid subclass of HTMLElement).

The solution

This crates provide the JavaScript shim necessary for extending an arbitrary subclass of HTMLElement and forwards all custom element lifecycle method calls to the Rust struct you provide.

Why this crate rather than the other available ones?

Allows creating both autonomous custom elements AND customized built-in elements
Provides all the valid HtmlElement constructors (behind a feature flag) for creating customized built-in elements
Comes with a comprehensive test suite
Extensive examples showing how to use this library to wrap Leptos components and call them from JS
Less opinionated approach to creating custom elements. This library

Current Rough Edges

It's possible to run into the following issue if you are calling your custom element with both &mut and & pointers: https://github.com/rustwasm/wasm-bindgen/issues/1578. The ways that I know of to get around this issue are by either by scheduling mutable calls to the custom element instance to happen once the current function scope ends or by adding some indirection through Rc<RefCell<T>> If you have other ideas of how to reduce this issue, I'd be interested in a message or a PR.