<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
    </head>
    <body>
        
        <script>
            const _getExFilename = (filename) => {
                // 补全代码
                let lastindex=filename.lastIndexOf('.')
              return filename.slice(0,lastindex) && lastindex !== -1 ? filename.slice(lastindex):''
            }
        </script>
    </body>
</html>