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The problem I'm having is that the dragleave event of an element is fired when hovering a child element of that element. Also, dragenter is not fired when hovering back the parent element again.

I made a simplified fiddle: /.

HTML:

<div id="drag" draggable="true">drag me</div>

<hr>

<div id="drop">
    drop here
    <p>child</p>
    parent
</div>

with the following JavaScript:

$('#drop').bind({
                 dragenter: function() {
                     $(this).addClass('red');
                 },

                 dragleave: function() {
                     $(this).removeClass('red');
                 }
                });

$('#drag').bind({
                 dragstart: function(e) {
                     e.allowedEffect = "copy";
                     e.setData("text/plain", "test");
                 }
                });

What it is supposed to do is notifying the user by making the drop div red when dragging something there. This works, but if you drag into the p child, the dragleave is fired and the div isn't red anymore. Moving back to the drop div also doesn't make it red again. It's necessary to move completely out of the drop div and drag back into it again to make it red.

Is it possible to prevent dragleave from firing when dragging into a child element?

2017 Update: TL;DR, Look up CSS pointer-events: none; as described in @H.D.'s answer below that works in modern browsers and IE11.

The problem I'm having is that the dragleave event of an element is fired when hovering a child element of that element. Also, dragenter is not fired when hovering back the parent element again.

I made a simplified fiddle: http://jsfiddle.net/pimvdb/HU6Mk/1/.

HTML:

<div id="drag" draggable="true">drag me</div>

<hr>

<div id="drop">
    drop here
    <p>child</p>
    parent
</div>

with the following JavaScript:

$('#drop').bind({
                 dragenter: function() {
                     $(this).addClass('red');
                 },

                 dragleave: function() {
                     $(this).removeClass('red');
                 }
                });

$('#drag').bind({
                 dragstart: function(e) {
                     e.allowedEffect = "copy";
                     e.setData("text/plain", "test");
                 }
                });

What it is supposed to do is notifying the user by making the drop div red when dragging something there. This works, but if you drag into the p child, the dragleave is fired and the div isn't red anymore. Moving back to the drop div also doesn't make it red again. It's necessary to move completely out of the drop div and drag back into it again to make it red.

Is it possible to prevent dragleave from firing when dragging into a child element?

2017 Update: TL;DR, Look up CSS pointer-events: none; as described in @H.D.'s answer below that works in modern browsers and IE11.

Share Improve this question edited Aug 25, 2019 at 17:33 Brian Tompsett - 汤莱恩 5,87572 gold badges61 silver badges133 bronze badges asked Aug 18, 2011 at 15:53 pimvdbpimvdb 155k80 gold badges311 silver badges356 bronze badges 8
  • The bug pimvdb reported still exists in Webkit as of May 2012. I've countered it by also adding a class in dragover, which isn't anywhere close to nice since it fires so often, but appears to patch the issue a bit. – ajm Commented May 11, 2012 at 18:35
  • 3 @ajm: Thanks, that works to an extent. However, on Chrome, there is a flash when entering or leaving the child element, presumably because dragleave is still fired in that case. – pimvdb Commented May 11, 2012 at 19:08
  • I have opened a jQuery UI bug upvotes are welcome so they can decide to put resources on it – fguillen Commented Aug 21, 2012 at 18:07
  • @fguillen: I'm sorry but this has nothing to do with jQuery UI. In fact, jQuery isn't even needed to trigger the bug. I've filed a WebKit bug already but there is no update as of now. – pimvdb Commented Aug 21, 2012 at 18:09
  • 2 I've found that the simplest solution to this really annoying problem, is to listen only to enter event on element, and when event fires - create an absolutely positioned overlay above given element, with only leave event listener. This removes neccesity of disabling pointer events on children (overlay takes over every drag event) and you are sure that leave will be fired when it should be. I've had this problem in vue component: always firing leave just after enter, didn't find out why really (children had pointer events set to none). – Przemysław Melnarowicz Commented Mar 9, 2020 at 12:24
 |  Show 3 more comments

41 Answers 41

Reset to default 1 2 Next 480

You just need to keep a reference counter, increment it when you get a dragenter, decrement when you get a dragleave. When the counter is at 0 - remove the class.

var counter = 0;

$('#drop').bind({
    dragenter: function(ev) {
        ev.preventDefault(); // needed for IE
        counter++;
        $(this).addClass('red');
    },

    dragleave: function() {
        counter--;
        if (counter === 0) { 
            $(this).removeClass('red');
        }
    }
});

Note: In the drop event, reset counter to zero, and clear the added class.

You can run it here

Is it possible to prevent dragleave from firing when dragging into a child element?

Yes.

#drop * {pointer-events: none;}

That CSS seem to be enough for Chrome.

While using it with Firefox, the #drop shouldn't have text nodes directly (else there's a strange issue where a element "leave it to itself"), so I suggest to leave it with only one element (e.g., use a div inside #drop to put everything inside)

Here's a jsfiddle solving the original question (broken) example.

I've also made a simplified version forked from the @Theodore Brown example, but based only in this CSS.

Not all browsers have this CSS implemented, though: http://caniuse.com/pointer-events

Seeing the Facebook source code I could find this pointer-events: none; several times, however it's probably used together with graceful degradation fallbacks. At least it's so simple and solves the problem for a lot of environments.

It has been quite some time after this question is asked and a lot of solutions (including ugly hacks) are provided.

I managed to fix the same problem I had recently thanks to the answer in this and thought it may be helpful to someone who comes across this page. The whole idea is to store the evenet.target in ondrageenter everytime it is called on any of the parent or child elements. Then in ondragleave check if the current target (event.target) is equal to the object you stored in ondragenter.

The only case these two are matched is when your drag is leaving the browser window.

The reason that this works fine is when the mouse leaves an element (say el1) and enters another element (say el2), first the el2.ondragenter is called and then el1.ondragleave. Only when the drag is leaving/entering the browser window, event.target will be '' in both el2.ondragenter and el1.ondragleave.

Here is my working sample. I have tested it on IE9+, Chrome, Firefox and Safari.

(function() {
  var bodyEl = document.body;
  var flupDiv = document.getElementById('file-drop-area');

  flupDiv.onclick = function(event) {
    console.log('HEy! some one clicked me!');
  };

  var enterTarget = null;

  document.ondragenter = function(event) {
    console.log('on drag enter: ' + event.target.id);
    enterTarget = event.target;
    event.stopPropagation();
    event.preventDefault();
    flupDiv.className = 'flup-drag-on-top';
    return false;
  };

  document.ondragleave = function(event) {
    console.log('on drag leave: currentTarget: ' + event.target.id + ', old target: ' + enterTarget.id);
    //Only if the two target are equal it means the drag has left the window
    if (enterTarget == event.target) {
      event.stopPropagation();
      event.preventDefault();
      flupDiv.className = 'flup-no-drag';
    }
  };
  document.ondrop = function(event) {
    console.log('on drop: ' + event.target.id);
    event.stopPropagation();
    event.preventDefault();
    flupDiv.className = 'flup-no-drag';
    return false;
  };
})();
<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8">
  <title>Multiple File Uploader</title>
  <link rel="stylesheet" href="my.css" />
</head>

<body id="bodyDiv">
  <div id="cntnr" class="flup-container">
    <div id="file-drop-area" class="flup-no-drag">blah blah</div>
  </div>
  <script src="my.js"></script>
</body>

</html>

With proper styling what I have done is to make the inner div (#file-drop-area) much bigger whenever a file is dragged into the screen so that the user can easily drop the files into the proper place.

This fairly simple solution is working for me so far, assuming your event is attached to each drag element individually.

if (evt.currentTarget.contains(evt.relatedTarget)) {
  return;
}

Here, the simplest Cross-Browser solution (seriously):

jsfiddle <-- try dragging some file inside the box

You can do something like that:

var dropZone= document.getElementById('box');
var dropMask = document.getElementById('drop-mask');

dropZone.addEventListener('dragover', drag_over, false);
dropMask.addEventListener('dragleave', drag_leave, false);
dropMask.addEventListener('drop', drag_drop, false);

In a few words, you create a "mask" inside the dropzone, with width & height inherited, position absolute, that will just show when the dragover starts.
So, after showing that mask, you can do the trick by attaching the others dragleave & drop events on it.

After leaving or dropping, you just hide the mask again.
Simple and without complications.

(Obs.: Greg Pettit advice -- You must be sure that the mask hover the entire box, including the border)

The "right" way to solve this issue is to disable pointer events on child elements of the drop target (as in @H.D.'s answer). Here's a jsFiddle I created which demonstrates this technique. Unfortunately, this doesn't work in versions of Internet Explorer prior to IE11, since they didn't support pointer events.

Luckily, I was able to come up with a workaround which does work in old versions of IE. Basically, it involves identifying and ignoring dragleave events which occur when dragging over child elements. Because the dragenter event is fired on child nodes before the dragleave event on the parent, separate event listeners can be added to each child node which add or remove an "ignore-drag-leave" class from the drop target. Then the drop target's dragleave event listener can simply ignore calls which occur when this class exists. Here's a jsFiddle demonstrating this workaround. It is tested and working in Chrome, Firefox, and IE8+.

Update:

I created a jsFiddle demonstrating a combined solution using feature detection, where pointer events are used if supported (currently Chrome, Firefox, and IE11), and the browser falls back to adding events to child nodes if pointer event support isn't available (IE8-10).

if you are using HTML5, you can get the parent's clientRect:

let rect = document.getElementById("drag").getBoundingClientRect();

Then in the parent.dragleave():

dragleave(e) {
    if(e.clientY < rect.top || e.clientY >= rect.bottom || e.clientX < rect.left || e.clientX >= rect.right) {
        //real leave
    }
}

here is a jsfiddle

A very simple solution is to use the pointer-events CSS property. Just set its value to none upon dragstart on every child element. These elements won't trigger mouse-related events anymore, so they won't catch the mouse over them and thus won't trigger the dragleave on the parent.

Don't forget to set this property back to auto when finishing the drag ;)

A simple solution is to add the css rule pointer-events: none to the child component to prevent the trigger of ondragleave. See example:

function enter(event) {
  document.querySelector('div').style.border = '1px dashed blue';
}

function leave(event) {
  document.querySelector('div').style.border = '';
}
div {
  border: 1px dashed silver;
  padding: 16px;
  margin: 8px;
}

article {
  border: 1px solid silver;
  padding: 8px;
  margin: 8px;
}

p {
  pointer-events: none;
  background: whitesmoke;
}
<article draggable="true">drag me</article>

<div ondragenter="enter(event)" ondragleave="leave(event)">
  drop here
  <p>child not triggering dragleave</p>
</div>

The problem is that the dragleave event is being fired when the mouse goes in front of the child element.

I've tried various methods of checking to see if the e.target element is the same as the this element, but couldn't get any improvement.

The way I fixed this problem was a bit of a hack, but works 100%.

dragleave: function(e) {
               // Get the location on screen of the element.
               var rect = this.getBoundingClientRect();

               // Check the mouseEvent coordinates are outside of the rectangle
               if(e.x > rect.left + rect.width || e.x < rect.left
               || e.y > rect.top + rect.height || e.y < rect.top) {
                   $(this).removeClass('red');
               }
           }

Very simple solution:

parent.addEventListener('dragleave', function(evt) {
    if (!parent.contains(evt.relatedTarget)) {
        // Here it is only dragleave on the parent
    }
}

I was having the same issue and tried to use pk7s solution. It worked but it could be done a little bit better without any extra dom elements.

Basicly the idea is same - add an extra unvisible overlay over droppable area. Only lets do this without any extra dom elements. Here is the part were CSS pseudo-elements come to play.

Javascript

var dragOver = function (e) {
    e.preventDefault();
    this.classList.add('overlay');
};

var dragLeave = function (e) {
    this.classList.remove('overlay');
};


var dragDrop = function (e) {
    this.classList.remove('overlay');
    window.alert('Dropped');
};

var dropArea = document.getElementById('box');

dropArea.addEventListener('dragover', dragOver, false);
dropArea.addEventListener('dragleave', dragLeave, false);
dropArea.addEventListener('drop', dragDrop, false);

CSS

This after rule will create a fully covered overlay for droppable area.

#box.overlay:after {
    content:'';
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    z-index: 1;
}

Here is the full solution: http://jsfiddle.net/F6GDq/8/

I hope it helps anyone with the same problem.

You can fix it in Firefox with a little inspiration from the jQuery source code:

dragleave: function(e) {
    var related = e.relatedTarget,
        inside = false;

    if (related !== this) {

        if (related) {
            inside = jQuery.contains(this, related);
        }

        if (!inside) {

            $(this).removeClass('red');
        }
    }

}

Unfortunately it doesn't work in Chrome because relatedTarget appears not to exist on dragleave events, and I assume you're working in Chrome because your example did't work in Firefox. Here's a version with the above code implemented.

And here it goes, a solution for Chrome:

.bind('dragleave', function(event) {
                    var rect = this.getBoundingClientRect();
                    var getXY = function getCursorPosition(event) {
                        var x, y;

                        if (typeof event.clientX === 'undefined') {
                            // try touch screen
                            x = event.pageX + document.documentElement.scrollLeft;
                            y = event.pageY + document.documentElement.scrollTop;
                        } else {
                            x = event.clientX + document.body.scrollLeft + document.documentElement.scrollLeft;
                            y = event.clientY + document.body.scrollTop + document.documentElement.scrollTop;
                        }

                        return { x: x, y : y };
                    };

                    var e = getXY(event.originalEvent);

                    // Check the mouseEvent coordinates are outside of the rectangle
                    if (e.x > rect.left + rect.width - 1 || e.x < rect.left || e.y > rect.top + rect.height - 1 || e.y < rect.top) {
                        console.log('Drag is really out of area!');
                    }
                })

Here's another solution using document.elementFromPoint:

 dragleave: function(event) {
   var event = event.originalEvent || event;
   var newElement = document.elementFromPoint(event.pageX, event.pageY);
   if (!this.contains(newElement)) {
     $(this).removeClass('red');
   }
}

Hope this works, here's a fiddle.

Not sure if this cross browser, but I tested in Chrome and it solves my problem:

I want to drag and drop a file over entire page, but my dragleave is fired when i drag over child element. My fix was to look at the x and y of mouse:

i have a div that overlays my entire page, when the page loads i hide it.

when you drag over document i show it, and when you drop on the parent it handles it, and when you leave the parent i check x and y.

$('#draganddrop-wrapper').hide();

$(document).bind('dragenter', function(event) {
    $('#draganddrop-wrapper').fadeIn(500);
    return false;
});

$("#draganddrop-wrapper").bind('dragover', function(event) {
    return false;
}).bind('dragleave', function(event) {
    if( window.event.pageX == 0 || window.event.pageY == 0 ) {
        $(this).fadeOut(500);
        return false;
    }
}).bind('drop', function(event) {
    handleDrop(event);

    $(this).fadeOut(500);
    return false;
});

An alternate working solution, a little simpler.

//Note: Due to a bug with Chrome the 'dragleave' event is fired when hovering the dropzone, then
//      we must check the mouse coordinates to be sure that the event was fired only when 
//      leaving the window.
//Facts:
//  - [Firefox/IE] e.originalEvent.clientX < 0 when the mouse is outside the window
//  - [Firefox/IE] e.originalEvent.clientY < 0 when the mouse is outside the window
//  - [Chrome/Opera] e.originalEvent.clientX == 0 when the mouse is outside the window
//  - [Chrome/Opera] e.originalEvent.clientY == 0 when the mouse is outside the window
//  - [Opera(12.14)] e.originalEvent.clientX and e.originalEvent.clientY never get
//                   zeroed if the mouse leaves the windows too quickly.
if (e.originalEvent.clientX <= 0 || e.originalEvent.clientY <= 0) {

Just check if the dragged over element is a child, if it is, then don't remove your 'dragover' style class. Pretty simple and works for me:

 $yourElement.on('dragleave dragend drop', function(e) {
      if(!$yourElement.has(e.target).length){
           $yourElement.removeClass('is-dragover');
      }
  })

I know this is a old question but wanted to add my preference. I deal with this by adding class triggered css :after element at a higher z-index then your content. This will filter out all the garbage.

.droppable{
    position: relative;
    z-index: 500;
}

.droppable.drag-over:after{
    content: "";
    display:block;
    position:absolute;
    left:0;
    right:0;
    top:0;
    bottom:0;
    z-index: 600;
}

Then just add the drag-over class on your first dragenter event and none of the child elements trigger the event any longer.

dragEnter(event){
 dropElement.classList.add('drag-over');
}

dragLeave(event){
 dropElement.classList.remove('drag-over');
}

I've stumbled into the same problem and here's my solution - which I think is much easier then above. I'm not sure if it's crossbrowser (might depend on even bubbling order)

I'll use jQuery for simplicity, but solution should be framework independent.

The event bubbles to parent either way so given:

<div class="parent">Parent <span>Child</span></div>

We attach events

el = $('.parent')
setHover = function(){ el.addClass('hovered') }
onEnter  = function(){ setTimeout(setHover, 1) }
onLeave  = function(){ el.removeClass('hovered') } 
$('.parent').bind('dragenter', onEnter).bind('dragleave', onLeave)

And that's about it. :) it works because even though onEnter on child fires before onLeave on parent, we delay it slightly reversing the order, so class is removed first then reaplied after a milisecond.

I've written a little library called Dragster to handle this exact issue, works everywhere except silently doing nothing in IE (which doesn't support DOM Event Constructors, but it'd be pretty easy to write something similar using jQuery's custom events)

I wrote a drag-and-drop module called drip-drop that fixes this weirdo behavior, among others. If you're looking for a good low-level drag-and-drop module you can use as the basis for anything (file upload, in-app drag-and-drop, dragging from or to external sources), you should check this module out:

https://github.com/fresheneesz/drip-drop

This is how you would do what you're trying to do in drip-drop:

$('#drop').each(function(node) {
  dripDrop.drop(node, {
    enter: function() {
      $(node).addClass('red')  
    },
    leave: function() {
      $(node).removeClass('red')
    }
  })
})
$('#drag').each(function(node) {
  dripDrop.drag(node, {
    start: function(setData) {
      setData("text", "test") // if you're gonna do text, just do 'text' so its compatible with IE's awful and restrictive API
      return "copy"
    },
    leave: function() {
      $(node).removeClass('red')
    }
  })
})

To do this without a library, the counter technique is what I used in drip-drop, tho the highest rated answer misses important steps that will cause things to break for everything except the first drop. Here's how to do it properly:

var counter = 0;    
$('#drop').bind({
    dragenter: function(ev) {
        ev.preventDefault()
        counter++
        if(counter === 1) {
          $(this).addClass('red')
        }
    },

    dragleave: function() {
        counter--
        if (counter === 0) { 
            $(this).removeClass('red');
        }
    },
    drop: function() {
        counter = 0 // reset because a dragleave won't happen in this case
    }
});

I found a simple solution to this problem so sharing it. It works well in my case.

jsfiddle try it.

You can actually achieve this only via the dragenter event and you don't even need to register a dragleave. All you need is to have a no-drop area around your dropzones and that's it.

You can also have nested dropzones and this works perfectly. Check this as well nested dropzones.

$('.dropzone').on("dragenter", function(e) {
  e.preventDefault();
  e.stopPropagation();
  $(this).addClass("over");
  $(".over").not(this).removeClass("over"); // in case of multiple dropzones
});

$('.dropzone-leave').on("dragenter", function(e) {
  e.preventDefault();
  e.stopPropagation();
  $(".over").removeClass("over");
});

// UPDATE
// As mar10 pointed out, the "Esc" key needs to be managed,
// the easiest approach is to detect the key and clean things up.

$(document).on('keyup', function(e){
  if (e.key === "Escape") {
    $(".over").removeClass("over");
  }
});

Just add this to child elements:

pointer-events: none;

After spending so many hours I got that suggestion working exactly as intended. I wanted to provide a cue only when files were dragged over, and document dragover, dragleave was causing painful flickers on Chrome browser.

This is how I solved it, also throwing in proper cues for user.

$(document).on('dragstart dragenter dragover', function(event) {    
    // Only file drag-n-drops allowed, http://jsfiddle.net/guYWx/16/
    if ($.inArray('Files', event.originalEvent.dataTransfer.types) > -1) {
        // Needed to allow effectAllowed, dropEffect to take effect
        event.stopPropagation();
        // Needed to allow effectAllowed, dropEffect to take effect
        event.preventDefault();

        $('.dropzone').addClass('dropzone-hilight').show();     // Hilight the drop zone
        dropZoneVisible= true;

        // http://www.html5rocks.com/en/tutorials/dnd/basics/
        // http://api.jquery.com/category/events/event-object/
        event.originalEvent.dataTransfer.effectAllowed= 'none';
        event.originalEvent.dataTransfer.dropEffect= 'none';

         // .dropzone .message
        if($(event.target).hasClass('dropzone') || $(event.target).hasClass('message')) {
            event.originalEvent.dataTransfer.effectAllowed= 'copyMove';
            event.originalEvent.dataTransfer.dropEffect= 'move';
        } 
    }
}).on('drop dragleave dragend', function (event) {  
    dropZoneVisible= false;

    clearTimeout(dropZoneTimer);
    dropZoneTimer= setTimeout( function(){
        if( !dropZoneVisible ) {
            $('.dropzone').hide().removeClass('dropzone-hilight'); 
        }
    }, dropZoneHideDelay); // dropZoneHideDelay= 70, but anything above 50 is better
});

"dragleave" event is fired when mouse pointer exits the dragging area of the target container.

Which makes a lot of sense as in many cases only the parent may be droppable and not the descendants. I think event.stopPropogation() should have handled this case but seems like it doesn't do the trick.

Above mentioned some solutions do seem to work for most of the cases, but fails in case of those children which does not support dragenter / dragleave events, such as iframe.

1 workaround is to check the event.relatedTarget and verify if it resides inside the container then ignore the dragleave event as I have done here:

function isAncestor(node, target) {
    if (node === target) return false;
    while(node.parentNode) {
        if (node.parentNode === target)
            return true;
        node=node.parentNode;
    }
    return false;
}

var container = document.getElementById("dropbox");
container.addEventListener("dragenter", function() {
    container.classList.add("dragging");
});

container.addEventListener("dragleave", function(e) {
    if (!isAncestor(e.relatedTarget, container))
        container.classList.remove("dragging");
});

You can find a working fiddle here!

Solved ..!

Declare any array for ex:

targetCollection : any[] 

dragenter: function(e) {
    this.targetCollection.push(e.target); // For each dragEnter we are adding the target to targetCollection 
    $(this).addClass('red');
},

dragleave: function() {
    this.targetCollection.pop(); // For every dragLeave we will pop the previous target from targetCollection
    if(this.targetCollection.length == 0) // When the collection will get empty we will remove class red
    $(this).removeClass('red');
}

No need to worry about child elements.

I struggeled a LOT with this, even after reading through all of these answers, and thought I may share my solution with you, because I figured it may be one of the simpler approaches, somewhat different though. My thought was of simply omitting the dragleave event listener completely, and coding the dragleave behaviour with each new dragenter event fired, while making sure that dragenter events won't be fired unnecessarily.

In my example below, I have a table, where I want to be able to exchange table row contents with each other via drag & drop API. On dragenter, a CSS class shall be added to the row element into which you're currently dragging your element, to highlight it, and on dragleave, this class shall be removed.

Example:

Very basic HTML table:

<table>
  <tr>
    <td draggable="true" class="table-cell">Hello</td>
  </tr>
  <tr>
    <td draggable="true" clas="table-cell">There</td>
  </tr>
</table>

And the dragenter event handler function, added onto each table cell (aside dragstart, dragover, drop, and dragend handlers, which are not specific to this question, so not copied here):

/*##############################################################################
##                              Dragenter Handler                             ##
##############################################################################*/

// When dragging over the text node of a table cell (the text in a table cell),
// while previously being over the table cell element, the dragleave event gets
// fired, which stops the highlighting of the currently dragged cell. To avoid
// this problem and any coding around to fight it, everything has been
// programmed with the dragenter event handler only; no more dragleave needed

// For the dragenter event, e.target corresponds to the element into which the
// drag enters. This fact has been used to program the code as follows:

var previousRow = null;

function handleDragEnter(e) {
  // Assure that dragenter code is only executed when entering an element (and
  // for example not when entering a text node)
  if (e.target.nodeType === 1) {
    // Get the currently entered row
    let currentRow = this.closest('tr');
    // Check if the currently entered row is different from the row entered via
    // the last drag
    if (previousRow !== null) {
      if (currentRow !== previousRow) {
        // If so, remove the class responsible for highlighting it via CSS from
        // it
        previousRow.className = "";
      }
    }
    // Each time an HTML element is entered, add the class responsible for
    // highlighting it via CSS onto its containing row (or onto itself, if row)
    currentRow.className = "ready-for-drop";
    // To know which row has been the last one entered when this function will
    // be called again, assign the previousRow variable of the global scope onto
    // the currentRow from this function run
    previousRow = currentRow;
  }
}

Very basic comments left in code, such that this code suits for beginners too. Hope this will help you out! Note that you will of course need to add all the event listeners I mentioned above onto each table cell for this to work.

You can use a timeout with a transitioning flag and listen on the top element. dragenter / dragleave from child events will bubble up to the container.

Since dragenter on the child element fires before dragleave of the container, we will set the flag show as transitioning for 1ms... the dragleave listener will check for the flag before the 1ms is up.

The flag will be true only during transitions to child elements, and will not be true when transitioning to a parent element (of the container)

var $el = $('#drop-container'),
    transitioning = false;

$el.on('dragenter', function(e) {

  // temporarily set the transitioning flag for 1 ms
  transitioning = true;
  setTimeout(function() {
    transitioning = false;
  }, 1);

  $el.toggleClass('dragging', true);

  e.preventDefault();
  e.stopPropagation();
});

// dragleave fires immediately after dragenter, before 1ms timeout
$el.on('dragleave', function(e) {

  // check for transitioning flag to determine if were transitioning to a child element
  // if not transitioning, we are leaving the container element
  if (transitioning === false) {
    $el.toggleClass('dragging', false);
  }

  e.preventDefault();
  e.stopPropagation();
});

// to allow drop event listener to work
$el.on('dragover', function(e) {
  e.preventDefault();
  e.stopPropagation();
});

$el.on('drop', function(e) {
  alert("drop!");
});

jsfiddle: http://jsfiddle.net/ilovett/U7mJj/

I had a similar problem — my code for hiding the dropzone on dragleave event for body was fired contatantly when hovering child elements making the dropzone flicker in Google Chrome.

I was able to solve this by scheduling the function for hiding dropzone instead of calling it right away. Then, if another dragover or dragleave is fired, the scheduled function call is cancelled.

body.addEventListener('dragover', function() {
    clearTimeout(body_dragleave_timeout);
    show_dropzone();
}, false);

body.addEventListener('dragleave', function() {
    clearTimeout(body_dragleave_timeout);
    body_dragleave_timeout = setTimeout(show_upload_form, 100);
}, false);

dropzone.addEventListener('dragover', function(event) {
    event.preventDefault();
    dropzone.addClass("hover");
}, false);

dropzone.addEventListener('dragleave', function(event) {
    dropzone.removeClass("hover");
}, false);

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