How to get a word under cursor using JavaScript?

If I for example have

<p> some long text </p>

on my HTML page, how can I know that cursor of mouse is for example above the word 'text'?

Answers:

Answer

Further to the two other answers, you may be able to split your paragraphs up into spans using jQuery (or javascript generally).

That way, you wouldn't need to think about outputting your text with spans around the words. Let your javascript do it for you.

e.g.

<p>Each word will be wrapped in a span.</p>
<p>A second paragraph here.</p>
Word: <span id="word"></span>

<script type="text/javascript">
    $(function() {
        // wrap words in spans
        $('p').each(function() {
            var $this = $(this);
            $this.html($this.text().replace(/\b(\w+)\b/g, "<span>$1</span>"));
        });

        // bind to each span
        $('p span').hover(
            function() { $('#word').text($(this).css('background-color','#ffff66').text()); },
            function() { $('#word').text(''); $(this).css('background-color',''); }
        );
    });
</script>

Note that the above code, while it works, will strip out any html inside your paragraph tags.

jsFiddle example

Answer

My other answer works only in Firefox. This answer works in Chrome. (Might work in Firefox, too, I don't know.)

function getWordAtPoint(elem, x, y) {
  if(elem.nodeType == elem.TEXT_NODE) {
    var range = elem.ownerDocument.createRange();
    range.selectNodeContents(elem);
    var currentPos = 0;
    var endPos = range.endOffset;
    while(currentPos+1 < endPos) {
      range.setStart(elem, currentPos);
      range.setEnd(elem, currentPos+1);
      if(range.getBoundingClientRect().left <= x && range.getBoundingClientRect().right  >= x &&
         range.getBoundingClientRect().top  <= y && range.getBoundingClientRect().bottom >= y) {
        range.expand("word");
        var ret = range.toString();
        range.detach();
        return(ret);
      }
      currentPos += 1;
    }
  } else {
    for(var i = 0; i < elem.childNodes.length; i++) {
      var range = elem.childNodes[i].ownerDocument.createRange();
      range.selectNodeContents(elem.childNodes[i]);
      if(range.getBoundingClientRect().left <= x && range.getBoundingClientRect().right  >= x &&
         range.getBoundingClientRect().top  <= y && range.getBoundingClientRect().bottom >= y) {
        range.detach();
        return(getWordAtPoint(elem.childNodes[i], x, y));
      } else {
        range.detach();
      }
    }
  }
  return(null);
}    

In your mousemove handler, call getWordAtPoint(e.target, e.x, e.y);

Answer

Preamble:

If you have multiple spans and nested HTML that separate words (or even characters in words), then all the above solutions will have trouble returning the full and correct word.

Here is an example from the bounty question: ?</span>r?0??. How to properly return ?r?0??? These issues were not addressed back in 2010, so I will present two solutions now (2015).


Solution 1 - Strip inner tags, wrap spans around each full word:

One solution is to strip out the span tags inside paragraphs but preserve their text. Split words and phrases are thus joined back together as regular text. Each word is found by whitespace division (not just a space), and those words are wrapped in spans which can be individually accessed.

In the demo, you can highlight the entire word and thus get the text of the whole word.


pic 0

Code:

$(function() {
  // Get the HTML in #hoverText - just a wrapper for convenience
  var $hoverText = $("#hoverText");

  // Replace all spans inside paragraphs with their text
  $("p span", $hoverText).each(function() {
    var $this = $(this);
    var text = $this.text(); // get span content
    $this.replaceWith(text); // replace all span with just content
  });

  // Wrap words in spans AND preserve the whitespace
  $("p", $hoverText).each(function() {
    var $this = $(this);
    var newText = $this.text().replace(/([\s])([^\s]+)/g, "$1<span>$2</span>");
    newText = newText.replace(/^([^\s]+)/g, "<span>$1</span>");
    $this.empty().append(newText);
  });

  // Demo - bind hover to each span
  $('#hoverText span').hover(
    function() { $(this).css('background-color', '#ffff66'); },
    function() { $(this).css('background-color', ''); }
  );
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<div id="hoverText">
  <p><span class="kinovar"><span id="selection_index3337" class="selection_index"></span>?? f7-?? ???? ?????1?? ??7e????? ???a?? ?? ????1???? ?3 ?? ????e?, ?r???? ??e???? t?e????????, ?3 ??e??: ?</span>r?0?? ????R??: <span class="kinovar">?? 
?????2. ?# ?? ??????? p??0??: ?</span>??c??2 ???E ??S ?D?: <span class="kinovar">?# ?3?????A. ?a?? ??fj??? n?h???z.</span>
  </p>
</div>

Solution 1 full-text demo


Solution 2 - Caret inspection and DOM traversal:

Here is a more sophisticated solution. It's an algorithmic solution using node traversal that accurately captures the full and correct word under a cursor in a text node.

A temporary word is found by checking the caret position (using caretPositionFromPoint or caretRangeFromPoint, credits for the idea to @chrisv). This may or may not be the full word, yet.

It is then analyzed to see if it is at either edge of its text node (beginning or end). If it is, the previous text node or the following text node is examined to see if it should be joined to make this word fragment longer.

Example:

?</span>r?0?? must return ?r?0??, not ? nor r?0??.

The DOM tree is traversed to get the next non-barrier text node. If two word fragments are separated by a <p> or some other barrier tag, then they are not adjacent and thus not part of the same word.

Example:

??.)</p><p>?? should not return ??.)??


In the demo, the left floating div is the word under the cursor. The right floating div, if visible, shows how a word on a boundary was formed. Other tags can safely be inline'd with the text in this solution.

pic 1

Code:

$(function() {
  // Get the HTML in #hoverText - just a wrapper for convenience
  var $hoverText = $("#hoverText");

  // Get the full word the cursor is over regardless of span breaks
  function getFullWord(event) {
     var i, begin, end, range, textNode, offset;
    
    // Internet Explorer
    if (document.body.createTextRange) {
       try {
         range = document.body.createTextRange();
         range.moveToPoint(event.clientX, event.clientY);
         range.select();
         range = getTextRangeBoundaryPosition(range, true);
      
         textNode = range.node;
         offset = range.offset;
       } catch(e) {
         return ""; // Sigh, IE
       }
    }
    
    // Firefox, Safari
    // REF: https://developer.mozilla.org/en-US/docs/Web/API/Document/caretPositionFromPoint
    else if (document.caretPositionFromPoint) {
      range = document.caretPositionFromPoint(event.clientX, event.clientY);
      textNode = range.offsetNode;
      offset = range.offset;

      // Chrome
      // REF: https://developer.mozilla.org/en-US/docs/Web/API/document/caretRangeFromPoint
    } else if (document.caretRangeFromPoint) {
      range = document.caretRangeFromPoint(event.clientX, event.clientY);
      textNode = range.startContainer;
      offset = range.startOffset;
    }

    // Only act on text nodes
    if (!textNode || textNode.nodeType !== Node.TEXT_NODE) {
      return "";
    }

    var data = textNode.textContent;

    // Sometimes the offset can be at the 'length' of the data.
    // It might be a bug with this 'experimental' feature
    // Compensate for this below
    if (offset >= data.length) {
      offset = data.length - 1;
    }

    // Ignore the cursor on spaces - these aren't words
    if (isW(data[offset])) {
      return "";
    }

    // Scan behind the current character until whitespace is found, or beginning
    i = begin = end = offset;
    while (i > 0 && !isW(data[i - 1])) {
      i--;
    }
    begin = i;

    // Scan ahead of the current character until whitespace is found, or end
    i = offset;
    while (i < data.length - 1 && !isW(data[i + 1])) {
      i++;
    }
    end = i;

    // This is our temporary word
    var word = data.substring(begin, end + 1);

    // Demo only
    showBridge(null, null, null);

    // If at a node boundary, cross over and see what 
    // the next word is and check if this should be added to our temp word
    if (end === data.length - 1 || begin === 0) {

      var nextNode = getNextNode(textNode);
      var prevNode = getPrevNode(textNode);

      // Get the next node text
      if (end == data.length - 1 && nextNode) {
        var nextText = nextNode.textContent;

        // Demo only
        showBridge(word, nextText, null);

        // Add the letters from the next text block until a whitespace, or end
        i = 0;
        while (i < nextText.length && !isW(nextText[i])) {
          word += nextText[i++];
        }

      } else if (begin === 0 && prevNode) {
        // Get the previous node text
        var prevText = prevNode.textContent;

        // Demo only
        showBridge(word, null, prevText);

        // Add the letters from the next text block until a whitespace, or end
        i = prevText.length - 1;
        while (i >= 0 && !isW(prevText[i])) {
          word = prevText[i--] + word;
        }
      }
    }
    return word;
  }

  // Return the word the cursor is over
  $hoverText.mousemove(function(e) {
    var word = getFullWord(e);
    if (word !== "") {
      $("#result").text(word);
    }
  });
});

// Helper functions

// Whitespace checker
function isW(s) {
  return /[ \f\n\r\t\v\u00A0\u2028\u2029]/.test(s);
}

// Barrier nodes are BR, DIV, P, PRE, TD, TR, ... 
function isBarrierNode(node) {
  return node ? /^(BR|DIV|P|PRE|TD|TR|TABLE)$/i.test(node.nodeName) : true;
}

// Try to find the next adjacent node
function getNextNode(node) {
  var n = null;
  // Does this node have a sibling?
  if (node.nextSibling) {
    n = node.nextSibling;

    // Doe this node's container have a sibling?
  } else if (node.parentNode && node.parentNode.nextSibling) {
    n = node.parentNode.nextSibling;
  }
  return isBarrierNode(n) ? null : n;
}

// Try to find the prev adjacent node
function getPrevNode(node) {
  var n = null;

  // Does this node have a sibling?
  if (node.previousSibling) {
    n = node.previousSibling;

    // Doe this node's container have a sibling?
  } else if (node.parentNode && node.parentNode.previousSibling) {
    n = node.parentNode.previousSibling;
  }
  return isBarrierNode(n) ? null : n;
}

// REF: http://stackoverflow.com/questions/3127369/how-to-get-selected-textnode-in-contenteditable-div-in-ie
function getChildIndex(node) {
  var i = 0;
  while( (node = node.previousSibling) ) {
    i++;
  }
  return i;
}

// All this code just to make this work with IE, OTL
// REF: http://stackoverflow.com/questions/3127369/how-to-get-selected-textnode-in-contenteditable-div-in-ie
function getTextRangeBoundaryPosition(textRange, isStart) {
  var workingRange = textRange.duplicate();
  workingRange.collapse(isStart);
  var containerElement = workingRange.parentElement();
  var workingNode = document.createElement("span");
  var comparison, workingComparisonType = isStart ?
    "StartToStart" : "StartToEnd";

  var boundaryPosition, boundaryNode;

  // Move the working range through the container's children, starting at
  // the end and working backwards, until the working range reaches or goes
  // past the boundary we're interested in
  do {
    containerElement.insertBefore(workingNode, workingNode.previousSibling);
    workingRange.moveToElementText(workingNode);
  } while ( (comparison = workingRange.compareEndPoints(
    workingComparisonType, textRange)) > 0 && workingNode.previousSibling);

  // We've now reached or gone past the boundary of the text range we're
  // interested in so have identified the node we want
  boundaryNode = workingNode.nextSibling;
  if (comparison == -1 && boundaryNode) {
    // This must be a data node (text, comment, cdata) since we've overshot.
    // The working range is collapsed at the start of the node containing
    // the text range's boundary, so we move the end of the working range
    // to the boundary point and measure the length of its text to get
    // the boundary's offset within the node
    workingRange.setEndPoint(isStart ? "EndToStart" : "EndToEnd", textRange);

    boundaryPosition = {
      node: boundaryNode,
      offset: workingRange.text.length
    };
  } else {
    // We've hit the boundary exactly, so this must be an element
    boundaryPosition = {
      node: containerElement,
      offset: getChildIndex(workingNode)
    };
  }

  // Clean up
  workingNode.parentNode.removeChild(workingNode);

  return boundaryPosition;
}

// DEMO-ONLY code - this shows how the word is recombined across boundaries
function showBridge(word, nextText, prevText) {
  if (nextText) {
    $("#bridge").html("<span class=\"word\">" + word + "</span>  |  " + nextText.substring(0, 20) + "...").show();
  } else if (prevText) {
    $("#bridge").html("..." + prevText.substring(prevText.length - 20, prevText.length) + "  |  <span class=\"word\">" + word + "</span>").show();
  } else {
    $("#bridge").hide();
  }
}
.kinovar { color:red; font-size:20px;}.slavic { color: blue;}#result {top:10px;left:10px;}#bridge { top:10px; right:80px;}.floater { position: fixed; background-color:white; border:2px solid black; padding:4px;}.word { color:blue;}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script> <div id="bridge" class="floater"></div> <div id="result" class="floater"></div> <div id="hoverText"><p><span class="kinovar"><span id="selection_index3337" class="selection_index"></span>?? f7-?? ???? ?????1?? ??7e????? ???a?? ?? ????1???? ?3 ?? ????e?, ?r???? ??e???? t?e????????, ?3 ??e??: ?</span>r?0?? ????R??: <span class="kinovar">?? ?????2. ?# ?? ??????? p??0??: ?</span>??c??2 ???E ??S ?D?: <span class="kinovar">?# ?3?????A. ?a?? ??fj??? n?h???z.</span></p><div class="slavic"> <input value="Works around other tags!"><p><span id="selection_index3737" class="selection_index"></span>(?. ?o7? ??.)</p><p><span class="kinovar"><span id="selection_index3738" class="selection_index"></span>?? ??0????? ?e????</span> </p><p><span class="kinovar"><span id="selection_index3739" class="selection_index"></span>t?a??? ??a?????? ?a???.</span></p><p><span class="kinovar"><span id="selection_index3740" class="selection_index"></span>?? f7-?? ???? ?????1?? ??7e????? ???a?? ?? ????1???? ?3 ?? ????e?, ?r???? ??e???? t?e????????, ?3 ??e??: ?</span>r?0?? ????R??: <span class="kinovar">?? ?????2. ?# ?? ??????? p??0??: ?</span>??c??2 ???E ??S ?D?: <span class="kinovar">?# ?3?????A. ?a?? ??fj??? n?h???z.<input value="Works around inline tags too"></span></p><p><span class="kinovar"><span id="selection_index3741" class="selection_index"></span>?? ?D? ?????a??: ??e?? ?????6?? ??????a???, ????a?w, ?? ?7. ??a?? ?7:</span></p></div>

(Note: I took the liberty of applying styles to the span tags that were present in your sample HTML to illuminate where text node borders are.)

Solution 2 full-text demo

(Working in Chrome and IE so far. For IE, a method from IERange had to be used as a shim for cross-browser compatibility)

Answer

To my knowledge, you can't.

Only thing I can think of is to put each of the words in their own element, then apply mouse over events to those elements.

<p><span>Some</span> <span>long</span> <span>text</span></p>

<script>
$(document).ready(function () {
  $('p span').bind('mouseenter', function () {
    alert($(this).html() + " is what you're currently hovering over!");
  });
});
</script>
Answer

There is an API for this in the current CSSOM View draft: document.caretPositionFromPoint(x,y)

You would have to check which browser supports this, though. Firefox 7 seems not to support it at all, whereas bug reports indicate Firefox 9 will. Chrome 14 supports caretRangeFromPoint(x,y) which is essentially the same, but from an older CSSOM draft.

Answer

Here is the solution for the bounty.

As suggested by chrisv you can use document.caretRangeFromPoint (chrome) or document.caretPositionFromPoint (Firefox). I think this solution better answer your question as it doesn't alter your text or the DOM.

This function return the word under the mouse cursor without altering the DOM:

From the document.caretRangeFromPoint documentation:

The caretRangeFromPoint() method of the Document interface returns a Range object for the document fragment under the specified coordinates.

From the document.caretPositionFromPoint documentation:

This method is used to retrieve the caret position in a document based on two coordinates. A CaretPosition is returned, containing the found DOM node and the character offset in that node.

The two function are slightly different but they both return the node containing the text and the offset of the cursor in this text. So it is easy to get the word under the mouse.

See the full example:

$(function () {
    function getWordUnderCursor(event) {
        var range, textNode, offset;

        if (document.body.createTextRange) {           // Internet Explorer
            try {
                range = document.body.createTextRange();
                range.moveToPoint(event.clientX, event.clientY);
                range.select();
                range = getTextRangeBoundaryPosition(range, true);
  
                textNode = range.node;
                offset = range.offset;
            } catch(e) {
                return "";
            }
        }
        else if (document.caretPositionFromPoint) {    // Firefox
            range = document.caretPositionFromPoint(event.clientX, event.clientY);
            textNode = range.offsetNode;
            offset = range.offset;
        } else if (document.caretRangeFromPoint) {     // Chrome
            range = document.caretRangeFromPoint(event.clientX, event.clientY);
            textNode = range.startContainer;
            offset = range.startOffset;
        }

        //data contains a full sentence
        //offset represent the cursor position in this sentence
        var data = textNode.data,
            i = offset,
            begin,
            end;

        //Find the begin of the word (space)
        while (i > 0 && data[i] !== " ") { --i; };
        begin = i;

        //Find the end of the word
        i = offset;
        while (i < data.length && data[i] !== " ") { ++i; };
        end = i;

        //Return the word under the mouse cursor
        return data.substring(begin, end);
    }

    //Get the HTML in a div #hoverText and detect mouse move on it
    var $hoverText = $("#hoverText");
    $hoverText.mousemove(function (e) {
        var word = getWordUnderCursor(e);
        
        //Show the word in a div so we can test the result
        if (word !== "") 
            $("#testResult").text(word);
    });
});

// This code make it works with IE
// REF: https://stackoverflow.com/questions/3127369/how-to-get-selected-textnode-in-contenteditable-div-in-ie
function getTextRangeBoundaryPosition(textRange, isStart) {
  var workingRange = textRange.duplicate();
  workingRange.collapse(isStart);
  var containerElement = workingRange.parentElement();
  var workingNode = document.createElement("span");
  var comparison, workingComparisonType = isStart ?
    "StartToStart" : "StartToEnd";

  var boundaryPosition, boundaryNode;

  // Move the working range through the container's children, starting at
  // the end and working backwards, until the working range reaches or goes
  // past the boundary we're interested in
  do {
    containerElement.insertBefore(workingNode, workingNode.previousSibling);
    workingRange.moveToElementText(workingNode);
  } while ( (comparison = workingRange.compareEndPoints(
    workingComparisonType, textRange)) > 0 && workingNode.previousSibling);

  // We've now reached or gone past the boundary of the text range we're
  // interested in so have identified the node we want
  boundaryNode = workingNode.nextSibling;
  if (comparison == -1 && boundaryNode) {
    // This must be a data node (text, comment, cdata) since we've overshot.
    // The working range is collapsed at the start of the node containing
    // the text range's boundary, so we move the end of the working range
    // to the boundary point and measure the length of its text to get
    // the boundary's offset within the node
    workingRange.setEndPoint(isStart ? "EndToStart" : "EndToEnd", textRange);

    boundaryPosition = {
      node: boundaryNode,
      offset: workingRange.text.length
    };
  } else {
    // We've hit the boundary exactly, so this must be an element
    boundaryPosition = {
      node: containerElement,
      offset: getChildIndex(workingNode)
    };
  }

  // Clean up
  workingNode.parentNode.removeChild(workingNode);

  return boundaryPosition;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
<b><div id="testResult"></div></b>
<div id="hoverText">   <p><span class="kinovar"><span id="selection_index3337" class="selection_index"></span>?? f7-?? ???? ?????1?? ??7e????? ???a?? ?? ????1???? ?3 ?? ????e?, ?r???? ??e???? t?e????????, ?3 ??e??: ?</span>r?0?? ????R??: <span class="kinovar">?? ?????2. ?# ?? ??????? p??0??: ?</span>??c??2 ???E ??S ?D?: <span class="kinovar">?# ?3?????A. ?a?? ??fj??? n?h???z.</span> </p> <div class="slavic"><p><span id="selection_index3737" class="selection_index"></span>(?. ?o7? ??.)</p> <p><span class="kinovar"><span id="selection_index3738" class="selection_index"></span>?? ??0????? ?e????</span></p> <p><span class="kinovar"><span id="selection_index3739" class="selection_index"></span>t?a??? ??a?????? ?a???.</span></p><p><span class="kinovar"><span id="selection_index3740" class="selection_index"></span>?? f7-?? ???? ?????1?? ??7e????? ???a?? ?? ????1???? ?3 ?? ????e?, ?r???? ??e???? t?e????????, ?3 ??e??: ?</span>r?0?? ????R??: <span class="kinovar">???????2. ?# ?? ??????? p??0??: ?</span>??c??2 ???E ??S ?D?: <span class="kinovar">?# ?3?????A. ?a?? ??fj??? n?h???z.</span> </p><p><span class="kinovar"><span id="selection_index3741" class="selection_index"></span>?? ?D? ?????a??: ??e?? ?????6?? ??????a???, ????a?w, ?? ?7. ??a?? ?7:</span> </p><p><span class="kinovar"><span id="selection_index3742" class="selection_index"></span>?</span>???h? ????1????z, ?? ???e?? ?0????? ????0????: ?3?A ??? ??B?? ?a?? ????1???????? ????1??z ???8 ????; (?. ?o7?) ?3?A ??? ?? ??????? k?h?w?? ????1??z ?? ?????e???; ?? ??????s??z ??????a??: ????A ?0??, ????A ?e??; ?? ?????1?? ??2 ?0?? ?a??????w ??????a??z, ?? ??1???? ?l??? ??s???, ???E ?? ?????? ???E ????a????w. ?? ????1 ?? ?z ?r?E ?9?, ???1??? ?? ?S, ?3 ????1??? ?S.</p></div></div>

Answer

Here's a simple solution that works in Chrome for most cases:

function getWordAtPoint(x, y) {
  var range = document.caretRangeFromPoint(x, y);

  if (range.startContainer.nodeType === Node.TEXT_NODE) {
    range.expand('word');
    return range.toString().trim();
  }

  return null;
}

I leave filtering out punctuation and properly handling hyphenated words as an exercise to the reader :).

Answer

Aw yiss! Here is ho!

Simple as it is and whitout Jquery or any other framework Fiddle: https://jsfiddle.net/703c96dr/

It will put spans on each word and add a onmouseover and onomouseout function. I could create a simple class to make it more usable but the code is so simple that anyone can edit and use.

<p>This is my text example of word highlighting or, if you want, word hovering</p>
<p>This is another text example of word highlighting or, if you want, word hovering</p>

Simple code

function onmouseoverspan(){
    this.style.backgroundColor = "red";
}
function onmouseoutspan(){
    this.style.backgroundColor = "transparent";
}
var spans,p = document.getElementsByTagName("p");
for(var i=0;i<p.length;i++) {
    if(p[i]==undefined) continue;
    p[i].innerHTML = p[i].innerHTML.replace(/\b(\w+)\b/g, "<span>$1</span>");
    spans = p[i].getElementsByTagName("span")
    for(var a=0;a<spans.length;a++) {
        spans[a].onmouseover = onmouseoverspan;
        spans[a].onmouseout = onmouseoutspan;
    }
}
Answer

You would probably have to break up the paragraph so that each word was contained inside of its own separate <span> element and then add onmouseover event attributes to each of them.

..And I think you mean "<p>some long text</p>"; backslashes are not part of HTML.

Answer

In Firefox you can hook the mousemove event. The callback has one argument, e. In the callback, do this:

var range = HTTparent.ownerDocument.createRange();
range.selectNode(e.rangeParent);
var str = range.toString();
range.detach();

Now str has the entire text that the mouse was over. e.rangeOffset is the location of the mousepointer within that string. In your case, str would be "some long text" and e.rangeOffset would be 11 if you were over the "e" in "text".

This code will get a little confused if you are in the margins, for instance when the mouse pointer is on the same line as the text but after the end of it. To fix this, you need to check that you are actually on top of text. Here's the test:

if(e && e.rangeParent && e.rangeParent.nodeType == e.rangeParent.TEXT_NODE
   && e.rangeParent.parentNode == e.target)

This technique works in Firefox. Doesn't work in Chrome.

Answer

function escapeHtml(unsafe) {
  return unsafe
    .replace(/&/g, "&amp;")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;")
    .replace(/'/g, "&#039;");
}

// REF: http://stackoverflow.com/questions/3127369/how-to-get-selected-textnode-in-contenteditable-div-in-ie
function getChildIndex(node) {
  var i = 0;
  while( (node = node.previousSibling) ) {
    i++;
  }
  return i;
}

// All this code just to make this work with IE, OTL
// REF: http://stackoverflow.com/questions/3127369/how-to-get-selected-textnode-in-contenteditable-div-in-ie
function getTextRangeBoundaryPosition(textRange, isStart) {
  var workingRange = textRange.duplicate();
  workingRange.collapse(isStart);
  var containerElement = workingRange.parentElement();
  var workingNode = document.createElement("span");
  var comparison, workingComparisonType = isStart ?
    "StartToStart" : "StartToEnd";

  var boundaryPosition, boundaryNode;

  // Move the working range through the container's children, starting at
  // the end and working backwards, until the working range reaches or goes
  // past the boundary we're interested in
  do {
    containerElement.insertBefore(workingNode, workingNode.previousSibling);
    workingRange.moveToElementText(workingNode);
  } while ( (comparison = workingRange.compareEndPoints(
    workingComparisonType, textRange)) > 0 && workingNode.previousSibling);

  // We've now reached or gone past the boundary of the text range we're
  // interested in so have identified the node we want
  boundaryNode = workingNode.nextSibling;
  if (comparison == -1 && boundaryNode) {
    // This must be a data node (text, comment, cdata) since we've overshot.
    // The working range is collapsed at the start of the node containing
    // the text range's boundary, so we move the end of the working range
    // to the boundary point and measure the length of its text to get
    // the boundary's offset within the node
    workingRange.setEndPoint(isStart ? "EndToStart" : "EndToEnd", textRange);

    boundaryPosition = {
      node: boundaryNode,
      offset: workingRange.text.length
    };
  } else {
    // We've hit the boundary exactly, so this must be an element
    boundaryPosition = {
      node: containerElement,
      offset: getChildIndex(workingNode)
    };
  }

  // Clean up
  workingNode.parentNode.removeChild(workingNode);

  return boundaryPosition;
}

function onClick(event) {
  var elt = document.getElementById('info');
  elt.innerHTML = "";
  var textNode;
  var offset;
  // Internet Explorer
  if (document.body.createTextRange) {
		  elt.innerHTML = elt.innerHTML+("*************** IE **************<br/>");
      range = document.body.createTextRange();
      range.moveToPoint(event.clientX, event.clientY);
      range.select();
      range = getTextRangeBoundaryPosition(range, true);

      textNode = range.node;
      offset = range.offset;
      elt.innerHTML = elt.innerHTML + "IE ok, result: [" + escapeHtml(textNode.nodeName) + "]/[" + escapeHtml(textNode.textContent) + "] @" + offset + "</br>";

  }
  
  // Internet Explorer method 2
  if (document.body.createTextRange) {
		  elt.innerHTML = elt.innerHTML+("*************** IE, Method 2 **************<br/>");
      range = document.body.createTextRange();
      range.moveToPoint(event.clientX, event.clientY);
      range.select();
			var sel = document.getSelection();
      textNode = sel.anchorNode;
      offset = sel.anchorOffset;
      elt.innerHTML = elt.innerHTML + "IE M2 ok, result: [" + escapeHtml(textNode.nodeName) + "]/[" + escapeHtml(textNode.textContent) + "] @" + offset + "</br>";
  }  

  // Firefox, Safari
  // REF: https://developer.mozilla.org/en-US/docs/Web/API/Document/caretPositionFromPoint
  if (document.caretPositionFromPoint) {
		  elt.innerHTML = elt.innerHTML+("*************** Firefox, Safari **************<br/>");  
    range = document.caretPositionFromPoint(event.clientX, event.clientY);
    textNode = range.offsetNode;
    offset = range.offset;
    elt.innerHTML = elt.innerHTML + "caretPositionFromPoint ok, result: [" + escapeHtml(textNode.nodeName) + "]/[" + escapeHtml(textNode.textContent) + "] @" + offset + "</br>";
    // Chrome
    // REF: https://developer.mozilla.org/en-US/docs/Web/API/document/caretRangeFromPoint
  }
  if (document.caretRangeFromPoint) {
		  elt.innerHTML = elt.innerHTML+("*************** Chrome **************<br/>");  
    range = document.caretRangeFromPoint(event.clientX, event.clientY);
    textNode = range.startContainer;
    offset = range.startOffset;
    elt.innerHTML = elt.innerHTML + "caretRangeFromPoint ok, result: [" + escapeHtml(textNode.nodeName) + "]/[" + escapeHtml(textNode.textContent) + "] @" + offset + "</br>";
  }
}

document.addEventListener('click', onClick);
#info {
  position: absolute;
  bottom: 0;
  background-color: cyan;
}
<div class="parent">
  <div class="child">SPACE&nbsp;SPACE Bacon ipsum dolor amet <span>SPAN SPANTT SPOOR</span> meatball bresaola t-bone tri-tip brisket. Jowl pig picanha cupim SPAXE landjaeger, frankfurter spare ribs chicken. Porchetta jowl pancetta drumstick shankle cow spare ribs jerky
    tail kevin biltong capicola brisket venison bresaola. Flank sirloin jowl andouille meatball venison salami ground round rump boudin turkey capicola t-bone. Sirloin filet mignon tenderloin beef, biltong doner bresaola brisket shoulder pork loin shankle
    turducken shank cow. Bacon ball tip sirloin ham.
  </div>
  <div id="info">Click somewhere in the paragraph above</div>
</div>

My answer is derived from Drakes' "Solution 2 - Caret inspection and DOM traversal". Thanks a lot to Drakes for pointing to this solution!

However, there's two problems with Drakes' solution 2 when working on IE. (1) the offset as calculated is incorrect, and (2) too complex, lots of code.

See my demonstration on JSFiddle at here.

For problem 1, if you click somewhere at about the last line of the text, for example somewhere in "shoulder pork loin shankle turducken shank cow. Bacon ball tip sirloin ham.", you can notice the offset calculation is different with IE (original solution) and IE method 2 (my solution). Also, the results from IE method 2 (my solution) and from Chrome, Firefox are the same.

My solution is also much simpler. The trick is, after use TextRange to make selection at the absolute X/Y position, get a type of IHTMLSelection by calling document.getSelection(). This does not work for IE<9 but if that's OK for you, this method is much simpler. Another caveat is, with IE the method's side effect (same as the original method) is change of selection (i.e. losing user's original selection).

  // Internet Explorer method 2
  if (document.body.createTextRange) {
          elt.innerHTML = elt.innerHTML+("*************** IE, Method 2 **************<br/>");
      range = document.body.createTextRange();
      range.moveToPoint(event.clientX, event.clientY);
      range.select();
      var sel = document.getSelection();
      textNode = sel.anchorNode;
      offset = sel.anchorOffset;
      elt.innerHTML = elt.innerHTML + "IE M2 ok, result: [" + escapeHtml(textNode.nodeName) + "]/[" + escapeHtml(textNode.textContent) + "] @" + offset + "</br>";
  }  

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