extArray = new Array(".gif", ".jpg", ".png", ".tiff",".jpeg", ".tif", ".bmp");
function LimitAttach(file) {


allowSubmit = false;
if (!file) return false;
while (file.indexOf("\\") != -1)
file = file.slice(file.indexOf("\\") + 1);
ext = file.slice(file.indexOf(".")).toLowerCase();
for (var i = 0; i < extArray.length; i++) {
if (extArray[i] == ext) { allowSubmit = true; break; }
}
if (!allowSubmit) 
{
alert("Please only upload files that end in types:  " 
+ (extArray.join("  ")) + "\nPlease select a new "
+ "file to upload and submit again.");
return false;
}
else
return true;
}