jQuery dragenter or dragover to include children

Solved it!!

It is a simple case of instead on on('dragenter') I needed to use bind('dragover')

$(document).ready(function(){
    $(window).on('dragenter', function(){
        $(this).preventDefault();
    });
    $('#drag-and-drop-zone').bind('dragover', function(){
        $(this).addClass('drag-over');
    });
    $('#drag-and-drop-zone').bind('dragleave', function(){
        $(this).removeClass('drag-over');
    });
});
.uploader
{
    width: 100%;
    background-color: #f9f9f9;
    color: #92AAB0;
    text-align: center;
    vertical-align: middle;
    padding: 30px 0px;
    margin-bottom: 10px;
    border-radius: 5px;
    font-size: 200%;
    box-shadow: inset 0px 0px 20px #c9afb2;
    cursor: default;
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

.uploader div.or {
    font-size: 50%;
    font-weight: bold;
    color: #C0C0C0;
    padding: 10px;
}

.uploader div.browser label {
    background-color: #ffffff;
    border: 2px solid #f44;
    padding: 5px 15px;
    color: #f44;
    padding: 6px 0px;
    font-size: 40%;
    font-weight: bold;
    cursor: pointer;
    border-radius: 2px;
    position: relative;
    overflow: hidden;
    display: block;
    width: 300px;
    margin: 20px auto 0px auto;
    transition: all 0.3s linear 0s;
}

.uploader div.browser span {
    cursor: pointer;
}

.uploader div.browser input {
    position: absolute;
    top: 0;
    right: 0;
    margin: 0;
    border: solid transparent;
    border-width: 0 0 100px 200px;
    opacity: .0;
    filter: alpha(opacity= 0);
    direction: ltr;
    cursor: pointer;
}

.uploader div.browser label:hover {
    background-color: #f44;
    color: #fff;
    border: 2px solid #fff;
}

.drag-over{
    border: 2px solid #00aef0;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.3/jquery.min.js"></script>
<div class="uploader" id="drag-and-drop-zone">
    <div>Drag &amp; Drop Images Here</div>
    <div class="or">-or-</div>
    <div class="browser">
        <label>
            <span>Select Image</span>
            <input type="file" title="Click to add Images" accept="image/*" name="files" disabled="true">
        </label>
    </div>
</div>

Apparently this problem is more recurrent than I thought since I found at least 5 questions associated with the same topic.

Unlike "mouseover", the events "dragover" and "dragleave" do not consider the child elements as a whole, so each time the mouse passes over any of the children, "dragleave" will be triggered.

Thinking about the upload of files, I created a widget that allows:

  1. Drag and drop desktop files using $ _FILES
  2. Drag and drop to browser images/elements or url using $ _POST and cURL
  3. Attach a device file using button using $ _FILES
  4. Use input to write/paste url images/elements using $ _POST and cURL

enter image description here

The problem: As everything, both form inputs and images, are within DIVs children, "dragleave" was triggered even if it did not leave the dashed line. Using the attribute "pointer-events: none" is not an alternative since methods 3 and 4 need to trigger "onchange" events.

The solution? An overlapping DIV that covers all the drop-container when the mouse enters, and the only one with child elements with "pointer-events: none".

The structure:

  • div #drop-container: main div, keep all togheter
  • div #drop-area: "dragenter" listener and inmediate trigger #drop-pupup
  • div #drop-pupup: at same leval as #drop-area, "dragenter", "dragleave" and "drop" listener

Then, when the mouse enters by dragging an element to #drop-area, inmediatly shows #drop-pupup ahead and successively the events are on this div and not the initial receiver.

enter image description here

Here is the JS/jQuery code. I took the liberty to leave the PoC so do not lose all the time I lost.

jQuery(document).on('dragover', '#drop-area', function(event) {
	event.preventDefault();
	event.stopPropagation();
	jQuery('#drop-popup').css('display','block');
});

jQuery(document).on('dragover dragleave drop', '#drop-popup', function(event) {
	event.preventDefault();
	event.stopPropagation();

	console.log(event.type);

	// layout and drop events
	if ( event.type == 'dragover') {
		jQuery('#drop-popup').css('display','block');
	}
	else {
		jQuery('#drop-popup').css('display','none');
	
		if ( event.type == 'drop' ) {
			// do what you want to do
			// for files: use event.originalEvent.dataTransfer.files
			// for web dragged elements: use event.originalEvent.dataTransfer.getData('Text') and CURL to capture
		}
	}
});
body {
  background: #ffffff;
  margin: 0px;
  font-family: sans-serif;
}

#drop-container {
  margin: 100px 10%; /* for online testing purposes only */
  width: 80%; /* for jsfiddle purposes only */
  display: block;
  float: left;
  overflow: hidden;
  box-sizing: content-box;
  position: relative; /* needed to use absolute on #drop-popup */
  border-radius: 5px;
  text-align: center;
  cursor: default;
  border: 2px dashed #000000;
}

#drop-area {
  display: block;
  float: left;
  padding: 10px;
  width: 100%;
}

#drop-popup {
  display: none;
  box-sizing: content-box;
  position: absolute;
  width: 100%;
  top: 0;
  left: 0;
  background: linear-gradient(to BOTTOM, rgba(245, 245, 245, 1) , rgba(245, 245, 245, 0));
  height: 512px;
  padding: 20px;
  z-index: 20;
}

#drop-popup > p {
   pointer-events: none;
}
<html>
  <head>
    <title>Drag and Drop</title>
  </head>
  <body>

    <div id="drop-container">
      <div id="drop-area">
        <p>Child paragraph content inside drop area saying "drop a file or an image in the dashed area"</p>
        <div>This is a child div No. 1</div>
        <div>This is a child div No. 2</div>
      </div>
      <div id="drop-popup">
        <p>This DIV will cover all childs on main DIV dropover event and current P tag is the only one with CSS "pointer-events: none;"</p>
      </div>
    </div>
    
    <script src="https://code.jquery.com/jquery-3.4.1.min.js" type="text/javascript"></script>
  </body>
<html>

About jQuery "on", use it with the div id inside on, so you can start event triggers starting "uploading box" hidden.

Finally, I preferred to use "dragover" over "dragenter" because it has a small delay (milliseconds) that favors performance (https://developer.mozilla.org/en-US/docs/Web/API/Document/dragover_event).