vant/packages/tabs/utils.ts

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();
}