Function attachTouch

src/index.ts:256–286

(el, props)

   *
   */
  const attachTouch: AttachTouch = (el, props) => {
    let cleanup = () => {};
    if (el && el.addEventListener) {
      const baseOptions = {
        ...defaultProps.touchEventOptions,
        ...props.touchEventOptions,
      };
      // attach touch event listeners and handlers
      const tls: [
        typeof touchStart | typeof touchMove | typeof touchEnd,
        (e: HandledEvents) => void,
        { passive: boolean }
      ][] = [
        [touchStart, onStart, baseOptions],
        // preventScrollOnSwipe option supersedes touchEventOptions.passive
        [
          touchMove,
          onMove,
          {
            ...baseOptions,
            ...(props.preventScrollOnSwipe ? { passive: false } : {}),
          },
        ],
        [touchEnd, onEnd, baseOptions],
      ];
      tls.forEach(([e, h, o]) => el.addEventListener(e, h, o));
      // return properly scoped cleanup method for removing listeners, options not required
      cleanup = () => tls.forEach(([e, h]) => el.removeEventListener(e, h));
    }
    return cleanup;
  };

  const onRef = (el: HTMLElement | null) => {
    // "inline" ref functions are called twice on render, once with null then again with DOM element