_title = function ( config )
{
	var title = config.title;

	if ( typeof title === 'function' ) {
		title = title();
	}

	return title.indexOf( '*' ) !== -1 ?
		title.replace( '*', $('title').text() || 'Exported data' ) :
		title;
}
Get the title for an exported file.

@param {object}  config  Button configuration