throw an alert if no data is entered

farp.php

@@ -23,6 +23,8 @@
         $myfile = fopen("posts.txt", "w") or die("Unable to open file!");
         fwrite($myfile, $content);
         fclose($myfile);
+    } else {
+        echo '<script>alert("Please draw something.")</script>';
     }
     ?>