Throw looking OK-ish

src/power.ts

@@ -0,0 +1,16 @@
+export class Power {
+    node: HTMLDivElement;
+
+    constructor() {
+        const node = document.getElementById("Power");
+        if (!node) {
+            throw new Error("no power");
+        }
+
+        this.node = node as HTMLDivElement;
+    }
+
+    setPower = (power: number) => {
+        this.node.style.width = power * 100 + "%";
+    }
+}