You could also handle the error conditional checking and JS alert output via PHP, eg:
$(document).ready( function() {
<?php
switch(error_for('fileTmpLoc')) {
case 1 : echo 'alert("Error: No image was selected.");';
break;
case 2 : echo 'alert("Error: Your file was too large. It was larger than 3.5 Megabytes in size.");';
break;
case 3 : echo 'alert("Error: Your file is too small. It was smaller than 200 KB in size.");';
break;
}
?>
});