Drag and Drop Zone opening file instead of uploading to server - php

Question

I have a file upload zone, one that let's you choose the file while the other is a drag and drop file upload zone.
Choosing file and clicking submit works perfectly fine.
The drag and drop zone however opens/downloads the file instead of uploading.
I think my PHP code is correct, because the file is getting correctly uploaded to server on choosing and uploading.
This is the JQuery code where I think there's a possible error.
+ function($) {
'use strict';
// UPLOAD CLASS DEFINITION
// ======================
var dropZone = document.getElementById('drop-zone');
var uploadForm = document.getElementById('js-upload-form');
var startUpload = function(files) {
console.log(files)
}
uploadForm.addEventListener('submit', function(e) {
var uploadFiles = document.getElementById('js-upload-files').files;
e.preventDefault()
startUpload(uploadFiles)
})
dropZone.ondrop = function(e) {
e.preventDefault();
this.className = 'upload-drop-zone';
startUpload(e.dataTransfer.items)
}
dropZone.ondragover = function() {
this.className = 'upload-drop-zone drop';
return false;
}
dropZone.ondragleave = function() {
this.className = 'upload-drop-zone';
return false;
}
}(jQuery);
Here's the HTML for a better reference:
<div class="container">
<div class="panel panel-default">
<div class="panel-heading"><strong>Upload CSV File</strong> <small>Insert Leads to MongoDB</small></div>
<div class="panel-body">
<!-- Standard Form -->
<h4>Select files from your computer</h4>
<form action="" method="post" enctype="multipart/form-data" id="js-upload-form">
<div class="form-inline">
<div class="form-group">
<input type="file" name="file" id="js-upload-files">
</div>
<button type="submit" class="btn btn-sm btn-primary" id="js-upload-submit">Upload files</button>
</div>
</form>
<!-- Drop Zone -->
<h4>Or drag and drop files below</h4>
<div class="upload-drop-zone" id="drop-zone">
Just drag and drop files here
</div>
</div>
</div>
I want the drag and drop zone to upload the file to server as well instead of opening.