How to find out the actual event.target of touchmove javascript event?

That's certainly not how event targets are supposed to work. Yet another DOM inconsistency that we're probably all now stuck with forever, due to a vendor coming up with extensions behind closed doors without any review.

Use document.elementFromPoint to work around it.

document.elementFromPoint(event.clientX, event.clientY);

So touch events have different "philosophy" when it comes to how they interact:

• Mouse moves = "hover" like behavior
• Touch moves = "drags" like behavior

This difference comes from the fact that there can not be a touchmove without touchstart event preceding it as a user has to touch screen to start this interaction. With mouse of course a user can mousemove all over the screen without ever pressing buttoon (mousedown event)

This is why basically we can't hope to use things like hover effects with touch:

element:hover { 
    background-color: yellow;
}

And this is why when user touches the screen with 1 finger the first event (touchstart) acquires the target element and the subsequent events (touchmove) will hold the reference to the original element where touch started. It feels wrong but there is this logic that you might need original target info as well. So ideally in future there should be both (source target and current target) available.

So common practice of today (2018) where screens can be mouse AND touch at the same time is still to attach both listeners (mouse and touch) and then "normalize" event coordinates and use above mentioned browser api to find element in those coordinates:

  // get coordinates depending on pointer type:
  var xcoord = event.touches? event.touches[0].pageX : event.pageX;
  var ycoord = event.touches? event.touches[0].pageY : event.pageY;
  // get element in coordinates:
  var targetElement = document.elementFromPoint(xcoord, ycoord);
  // validate if this is a valid element for our case:
  if (targetElement && targetElement.classList.contains("dropZone")) {
  }

Try using event.target.releasePointerCapture(event.pointerId) in the pointerdown handler.

We're now in 2022, this is intended and specified behavior - it's called "Implict Pointer Capture"

See the W3 spec on Pointer Events

Direct manipulation devices should behave exactly as if setPointerCapture was called on the target element just before the invocation of any pointerdown listeners. The hasPointerCapture API may be used (eg. within any pointerdown listener) to determine whether this has occurred.

elementFromPoint is a possible solution, but it seems you can also use releasePointerCapture as shown in the following demo. Touching and holding on the green div will get mouse move events for targets outside of it, whereas the red div has the default behavior.

const outputDiv = document.getElementById('output-div');
const releaseDiv = document.getElementById('test-release-div');
const noreleaseDiv = document.getElementById('test-norelease-div');

releaseDiv.addEventListener('pointerdown', function(e) {
  outputDiv.innerHTML = "releaseDiv-pointerdown";
  if (e.target.hasPointerCapture(e.pointerId)) {
      e.target.releasePointerCapture(e.pointerId);
  }
});

noreleaseDiv.addEventListener('pointerdown', function(e) {
  outputDiv.innerHTML = "noreleaseDiv-pointerdown";
});

document.addEventListener('pointermove', function(e) {
  outputDiv.innerHTML = e.target.id;
});

<div id="output-div"></div>
<div id="test-release-div" style="width:300px;height:100px;background-color:green;touch-action:none;user-select:none">Touch down here and move around, this releases implicit pointer capture</div>

<div id="test-norelease-div" style="width:300px;height:100px;background-color:red;touch-action:none;user-select:none">Touch down here and move around, this doesn't release implicit pointer capture<div>

JSP64's answer didn't fully work since event.originalEvent always returned undefined. A slight modification as follows works now.

var myLocation = event.touches[0];
var realTarget = document.elementFromPoint(myLocation.clientX, myLocation.clientY);