change dir stucture

public/gameloop.js

@@ -0,0 +1,31 @@
+export const run = options => {
+  const fps = options.fps || 60
+  const slow = options.slow || 1
+  const update = options.update
+  const render = options.render
+  const raf = window.requestAnimationFrame
+  const step = 1 / fps
+  const slowStep = slow * step
+
+  let now
+  let dt = 0
+  let last = window.performance.now()
+
+  const frame = () => {
+    now = window.performance.now()
+    dt = dt + Math.min(1, (now - last) / 1000) // duration capped at 1.0 seconds
+    while (dt > slowStep) {
+      dt = dt - slowStep
+      update(step)
+    }
+    render(dt / slow)
+    last = now
+    raf(frame)
+  }
+
+  raf(frame)
+}
+
+export default {
+  run
+}