Javascript Image Validation

Image Validation using JavaScript.

function isValidImage(imagename)
{
 imagefile_value = imagename;
 var checking = imagefile_value.toLowerCase();
 if (!checking.match(/(\.jpg|\.gif|\.png|\.JPG|\.GIF|\.PNG|\.jpeg|\.JPEG)$/))
 {
  return false;
 }
 else
 {
  return true;
 }
}