index.html

<!DOCTYPE html>
<html>
<head>
	 <title>Drag and drop file upload with php</title>
	 <link rel="stylesheet" href="dropzone.css">
</head>
<body>
     <form action="uploadHandler.php" class="dropzone image-uploader"></form>

     <script src="dropzone.js"></script>
	 <script type="text/javascript">
	    $(document).ready(function () {
	 
	    Dropzone.options.myAwesomeDropzone = {
	        paramName: "file", // The name that will be used to transfer the file
	        maxFilesize: 20, // MB
	        dictDefaultMessage: "Drop files here or click to upload",
			parallelUploads: 1,
	        accept: function (file, done) {
	            if (file.name == "justinbieber.jpg") {
	                done("Naha, you don't.");
	            }
	            else {
	                done();
	            }
	        }
	    };
	</script>


</body>
</html>