Random error: TypeError: Cannot read properties of undefined (reading 'left')

[usanzadunje]

I am using interact.js in my Ionic + Vue project. I have screen where there is on circle on screen when it is dragged it is cloned into parent element. Code is shown below. This works most of the time in real browser (not 100%). But on my mobile I always get this weird error and I do not understand why. I tried to figure out why and where it is comming from but it is internal error from your code. I tracked bug down to this line of code :

interaction.start({ name: "drag" }, event.interactable, element);

   .on('move', dragOrClone); // this function that cases error is called on this line of global interact instance

    const dragOrClone = (event) => {
      const { currentTarget, interaction } = event;
      let element = currentTarget;

      if(
          interaction.pointerIsDown &&
          !interaction.interacting() &&
          currentTarget.style.transform === ""
      ) {
        element = currentTarget.cloneNode(true);

        element.style.position = "absolute";
        element.style.left = 0;
        element.style.top = 0;
        element.style.width = '24px';
        element.style.height = '24px';
        element.style.transform = 'translate(0px, 0px)';
        element.classList.remove('bg-yellow-800');
        element.classList.add('bg-yellow-600');

        // Adding object inside parent container element
        dropzone && dropzone.appendChild(element);

        position.x = 0;
        position.y = 0;

        // If we are moving an already existing item, we need to make sure the position object has
        // the correct values before we start dragging it
      }else if(
          interaction.pointerIsDown &&
          !interaction.interacting()
      ) {
        updatePositionFromTransform(currentTarget);
      }

      // Start the drag event
      interaction.start({ name: "drag" }, event.interactable, element);
    };

Edit : Also this circle that is used for cloning others does not have transform value so if statement which cloned object can be true. But when I but transform on it I do not see this error but this then breaks my intention of cloning object.

[kjarrith]

+1

[kjarrith]

@usanzadunje - did you manage to find a solution to this?

[taye]

Can you try if using a down event instead of move to start the interaction helps?

[taye]

Also, an unminified stacktrace would be useful

[mcf11y]

Hi, @taye, faced the same problem. As a result of searching, I found that in: https://github.com/taye/interact.js/blob/9c280e4e6557ff3732678d1c387250a3801d6e05/packages/%40interactjs/utils/domUtils.ts#L212 should always returns Rect, but there may be a situation when it is not possible to get ClientRect in https://github.com/taye/interact.js/blob/9c280e4e6557ff3732678d1c387250a3801d6e05/packages/%40interactjs/utils/domUtils.ts#L213-L214 this is due to element.getClientRects()[0], A possible solution to this problem would be always returns Rect with zeros in:https://github.com/taye/interact.js/blob/9c280e4e6557ff3732678d1c387250a3801d6e05/packages/%40interactjs/utils/domUtils.ts#L217-L225 for example so:

if (clientRect == null) {
  return {
    left: 0,
    right: 0,
    top: 0,
    bottom: 0,
    width: 0,
    height: 0,
  };
}

return {
  left: clientRect.left,
  right: clientRect.right,
  top: clientRect.top,
  bottom: clientRect.bottom,
  width: clientRect.width || clientRect.right - clientRect.left,
  height: clientRect.height || clientRect.bottom - clientRect.top,
};