Make sure effects run on reattach

Also handled situation where teardown was ran multiple times when
reattaching.

Fixes #58

Author: cristinecula

src/create-effect.ts

@@ -40,9 +40,16 @@ function createEffect(setEffects: (state: State, cb: Callable) => void) {
         this._teardown = this.callback.call(this.state);
       }
 
-      teardown(): void {
+      teardown(disconnected?: boolean): void {
         if (typeof this._teardown === "function") {
           this._teardown();
+          // ensure effect is not torn down multiple times
+          this._teardown = undefined;
+        }
+
+        // reset to pristine state when element is disconnected
+        if (disconnected) {
+          this.lastValues = this.values = undefined;
         }
       }
 

src/hook.ts

@@ -12,7 +12,7 @@ abstract class Hook<P extends unknown[] = unknown[], R = unknown, H = unknown> {
   }
 
   abstract update(...args: P): R;
-  teardown?(): void;
+  teardown?(disconnected?: boolean): void;
 }
 
 interface CustomHook<

src/state.ts

@@ -55,7 +55,7 @@ class State<H = unknown> {
     let hooks = this[hookSymbol];
     hooks.forEach((hook) => {
       if (typeof hook.teardown === "function") {
-        hook.teardown();
+        hook.teardown(true);
       }
     });
   }