snapdrop/app/elements/file-sharing/file-drop-behavior.html

<script>
'use strict';
Chat = window.Chat || {};
Chat.FileDropBehavior = {
    attached: function() {
        var dropZone = this;

        // Optional.   Show the copy icon when dragging over.  Seems to only work for chrome.
        dropZone.addEventListener('dragover', function(e) {
            e.stopPropagation();
            e.preventDefault();
            e.dataTransfer.dropEffect = 'copy';
            this.style.transform = 'scale(1.2)';
        });

        // Get file data on drop
        dropZone.addEventListener('drop', function(e) {
            e.stopPropagation();
            e.preventDefault();
            var files = e.dataTransfer.files; // Array of all files
            for (var i = 0; i < files.length; i++) {
                var file = files[i];
                var reader = new FileReader();
                reader.onload = function(e2) {
                    // finished reading file data.
                    console.log('file dropped');
                    this.fire('file-uploaded', {
                        url: e2.target.result,
                        name: file.name
                    });
                }.bind(this);
                reader.readAsDataURL(file); // start reading the file data.
            }
        });
    }
}
</script>