DocumentOrShadowRoot.caretPositionFromPoint()

The caretPositionFromPoint() property of the DocumentOrShadowRoot interface returns a CaretPosition object, containing the DOM node, along with the caret and caret's character offset within that node.

var caretPosition = document.caretPositionFromPoint(float x, float y);

x

The horizontal coordinate of a point.

y

The vertical coordinate of a point.

A CaretPosition object.

This example inserts line breaks wherever you click. The code for it is below the demo.

<p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr,
sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat,
sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum.
Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.</p>

function insertBreakAtPoint(e) {
  var range;
  var textNode;
  var offset;

  if (document.caretPositionFromPoint) {
    range = document.caretPositionFromPoint(e.clientX, e.clientY);
    textNode = range.offsetNode;
    offset = range.offset;
  } else if (document.caretRangeFromPoint) {
    range = document.caretRangeFromPoint(e.clientX, e.clientY);
    textNode = range.startContainer;
    offset = range.startOffset;
  }

  // only split TEXT_NODEs
  if (textNode.nodeType == 3) {
    var replacement = textNode.splitText(offset);
    var br = document.createElement('br');
    textNode.parentNode.insertBefore(br, replacement);
  }
}

window.onload = function (){
  var paragraphs = document.getElementsByTagName("p");
  for (i=0 ; i < paragraphs.length; i++) {
    paragraphs[i].addEventListener("click", insertBreakAtPoint, false);
  }
};