Prevent browser from loading a drag-and-dropped file

Question

I\'m adding an html5 drag and drop uploader to my page.

When a file is dropped into the upload area, everything works great.

However, if I accidentally drop

Answer 1

I am using a class selector for multiple upload areas so my solution took this less pure form

Based on Axel Amthor's answer, with dependency on jQuery (aliased to $)

_stopBrowserFromOpeningDragAndDropPDFFiles = function () {

        _preventDND = function(e) {
            if (!$(e.target).is($(_uploadBoxSelector))) {
                e.preventDefault();
                e.dataTransfer.effectAllowed = 'none';
                e.dataTransfer.dropEffect = 'none';
            }
        };

        window.addEventListener('dragenter', function (e) {
            _preventDND(e);
        }, false);

        window.addEventListener('dragover', function (e) {
            _preventDND(e);
        });

        window.addEventListener('drop', function (e) {
            _preventDND(e);
        });
    },