ABout to try scene and script merger

types/asset/assetentry.d.ts

@@ -5,6 +5,24 @@
  * https://opensource.org/licenses/MIT
  */
 
+/**
+ * An array-like proxy over one of an asset entry's events.
+ * Assign a function to a numbered slot to subscribe; assign `null` to
+ * unsubscribe that slot.
+ *
+ * @example
+ * entry.onLoaded[0] = () => Console.print('loaded!');
+ * entry.onLoaded[0] = null; // unsubscribe
+ */
+interface AssetEventProxy {
+  readonly length: number;
+  0: (() => void) | null;
+  1: (() => void) | null;
+  2: (() => void) | null;
+  3: (() => void) | null;
+  toString(): string;
+}
+
 /**
  * A live reference to an entry in the asset cache.
  * Holds a lock that keeps the entry alive; the lock is released automatically
@@ -26,6 +44,12 @@ interface AssetEntry {
    * is not yet loaded.
    */
   readonly texture: Texture | undefined;
+  /** Event proxy — subscribe up to 4 callbacks for when loading completes. */
+  readonly onLoaded: AssetEventProxy;
+  /** Event proxy — subscribe up to 4 callbacks for when the entry is disposed. */
+  readonly onUnloaded: AssetEventProxy;
+  /** Event proxy — subscribe up to 4 callbacks for when loading fails. */
+  readonly onError: AssetEventProxy;
   /**
    * Blocks until the entry reaches `LOADED` (or `ERROR`).
    * Returns `this` for chaining.