Drag+Drop image uploader for SE chat

upload.user.js

// ==UserScript==
// @name Chat Image Upload
// @description Drag and Drop upload images
// @author fredley
// @version 1.0.0
// @include *://chat.meta.stackoverflow.com/rooms/*
// @include *://chat.meta.stackexchange.com/rooms/*
// @include *://chat.stackexchange.com/rooms/*
// @include *://chat.stackoverflow.com/rooms/*
// @include *://chat.askubuntu.com/rooms/*
// @include *://chat.serverfault.com/rooms/*
// @run-at document-end
// ==/UserScript==

function inject() {
    for (var i = 0; i < arguments.length; ++i) {
        if (typeof(arguments[i]) == 'function') {
            var script = document.createElement('script');
            script.type = 'text/javascript';
            script.textContent = '(' + arguments[i].toString() + ')(jQuery)';
            document.body.appendChild(script);
        }
    }
}

inject(function ($) {
    $(document).ready(function() {
        $('body').append('<div id="dropper"><h1>Upload image!</h1></div>');
        $('body').append('<style>#dropper{display:none;position:fixed;left:0;top:0;width:100%;height:100%;background:rgba(0,0,0,0.7);z-index:9999;}#dropper h1{text-align:center;padding-top:200px;position:absolute;width:100%;color:#FFF;font-size:450%;font-weight:bold;font-family:Helvetica;}</style>');
        $('body').on({
        dragenter: function(e){
            $('#dropper').show();
            e.preventDefault();
            e.stopPropagation();
        },
        dragover: function(e){
            $('#dropper').show();
            e.preventDefault();
            e.stopPropagation();
        },
        dragend: function(e){
            $('#dropper').hide();
            e.preventDefault();
            e.stopPropagation();
        },
        drop: function(e){
            $('#dropper').hide();
            if(e.originalEvent.dataTransfer && e.originalEvent.dataTransfer.files.length) {
                console.log('upload!');
                e.preventDefault();
                e.stopPropagation();
                var files = e.originalEvent.dataTransfer.files;
                initFileUpload().showDialog(function(a){
                    $('#input').val($('#input').val() + a);
                    $('#input').focus();
                });
                setTimeout(function(){
                    $('#filename-input').prop("files", files);
                    setTimeout(function(){
                        $('input[value="upload"]').click();
                    },20);
                },20);
            }
        }});
        $('#dropper').on('click',function(e){
            $(this).hide();
        });
    });
});