[improvement] rename packages dir to src (#3659)

src/tabs/utils.ts

@@ -0,0 +1,17 @@
+import { raf } from '../utils/dom/raf';
+
+export function scrollLeftTo(el: HTMLElement, to: number, duration: number) {
+  let count = 0;
+  const from = el.scrollLeft;
+  const frames = duration === 0 ? 1 : Math.round((duration * 1000) / 16);
+
+  function animate() {
+    el.scrollLeft += (to - from) / frames;
+
+    if (++count < frames) {
+      raf(animate);
+    }
+  }
+
+  animate();
+}