Merge pull request #197 from github/allow-hmr-plugins

Allow CustomElements to be redefined

package.json

@@ -53,7 +53,7 @@
  {
  "path": "lib/index.js",
  "import": "{controller, attr, target, targets}",
- "limit": "1.6kb"
+ "limit": "1.64kb"
  }
  ]
 }

src/register.ts

@@ -10,10 +10,17 @@ import {dasherize} from './dasherize.js'
  */
 export function register(classObject: CustomElement): void {
  const name = dasherize(classObject.name).replace(/-element$/, '')
- if (!window.customElements.get(name)) {
+
+ try {
+ window.customElements.define(name, classObject)
  // eslint-disable-next-line @typescript-eslint/ban-ts-comment
  // @ts-ignore
- window[classObject.name] = classObject
- window.customElements.define(name, classObject)
+ window[classObject.name] = customElements.get(name)
+ } catch (e: unknown) {
+ // The only reason for window.customElements.define to throw a `NotSupportedError`
+ // is if the element has already been defined.
+ if (e instanceof DOMException && e.name === 'NotSupportedError') return
+
+ throw e
  }
 }