source: main/waeup.kofa/branches/uli-fix-zc-async/layout/static/js/file-upload.js

$(document)
        .on('change', '.btn-file :file', function() {
                var input = $(this),
                numFiles = input.get(0).files ? input.get(0).files.length : 1,
                label = input.val().replace(/\\/g, '/').replace(/.*\//, '');
                input.trigger('fileselect', [numFiles, label]);
});

$(document).ready( function() {
        $('.btn-file :file').on('fileselect', function(event, numFiles, label) {

                var input = $(this).parents('.input-group').find(':text'),
                        log = numFiles > 1 ? numFiles + ' files selected' : label;

                if( input.length ) {
                        input.val(log);
                } else {
                        if( log ) alert(log);
                }
        });
});