var sizeBox = document.getElementById('sizeBox'), // container for file size info progress = document.getElementById('progress'); // the element we're using for a progress bar var uploader = new ss.SimpleUpload({ button: 'uploadButton', // file upload button url: 'uploadHandler.php', // server side handler name: 'uploadfile', // upload parameter name progressUrl: 'uploadProgress.php', // enables cross-browser progress support (more info below) responseType: 'json', allowedExtensions: ['jpg', 'jpeg', 'png', 'gif'], maxSize: 1024, // kilobytes hoverClass: 'ui-state-hover', focusClass: 'ui-state-focus', disabledClass: 'ui-state-disabled', onSubmit: function(filename, extension) { this.setFileSizeBox(sizeBox); // designate this element as file size container this.setProgressBar(progress); // designate as progress bar }, onComplete: function(filename, response) { if (!response) { alert(filename + 'upload failed'); return false; } // do something with response... } });