rewrite in typescript with LitElement

.gitignore

@@ -1,2 +1,5 @@
-/bower_components
-**/*~
+/node_modules
+*.js
+*.js.map
+*.d.ts
+!karma.conf.js

.vscode/settings.json

@@ -0,0 +1,7 @@
+{
+  "files.exclude": {
+    "**/*.js": {"when": "$(basename).ts"},
+    "**/*.d.ts": {"when": "$(basename).ts"},
+    "**/*.js.map": true
+  },
+}

base.ts

@@ -0,0 +1,34 @@
+import type { PropertyValues } from 'lit-element';
+import { FireMixin } from '@pwrs/mixins/fire';
+import { LitElement, property } from 'lit-element';
+import { bound } from './bound-decorator';
+
+type LeafletFeature =
+  | null
+  | L.Circle
+  | L.GeoJSON
+  | L.Marker
+  | L.LayerGroup
+  | L.Polyline
+  | L.Polygon
+  | L.Popup
+  | L.Point;
+
+export class LeafletBase extends FireMixin(LitElement) {
+  @property({ attribute: false }) container: L.Map | L.LayerGroup;
+
+  _mutationObserver?: MutationObserver;
+
+  feature: LeafletFeature;
+
+  containerChanged?(): void;
+
+  updated(changed: PropertyValues) {
+    super.updated?.(changed);
+    if (changed.has('container')) this.containerChanged?.();
+  }
+
+  @bound onLeafletEvent(e: L.LeafletEvent) {
+    this.fire(e.type, e);
+  }
+}

boilerplate.md

@@ -0,0 +1,5 @@
+```html
+<script src="https://unpkg.com/@webcomponentsjs/webcomponentsjs/webcomponents-loader.js"></script>
+<script type="module" src="https://unpkg.com/leaflet-element?module"></script>
+<leaflet-map></leaflet-map>
+```

bound-decorator.ts

@@ -0,0 +1,27 @@
+export function bound<T extends Function>(
+  target: object,
+  propertyKey: string,
+  descriptor: TypedPropertyDescriptor<T>
+): TypedPropertyDescriptor<T> | void {
+  if (!descriptor || typeof descriptor.value !== 'function') {
+    throw new TypeError(
+      `Only methods can be decorated with @bound. <${propertyKey}> is not a method!`
+    );
+  }
+
+  return {
+    configurable: true,
+    get(this: T): T {
+      const f: T = descriptor.value!.bind(this);
+      // Credits to https://github.com/andreypopp/autobind-decorator for memoizing the result of bind against a symbol on the instance.
+      Object.defineProperty(this, propertyKey, {
+        value: f,
+        configurable: true,
+        writable: true,
+      });
+      return f;
+    },
+  };
+}
+
+export default bound;