You can do it like this:
<?php
$phpArray = array("New York", "Chicago", "Houston", "Portland");
echo '<script language="JavaScript">'."\n";
echo '<!--'."\n";
echo 'var jsArray = new Array()'."\n";
reset($phpArray);
while (list ($key, $value) = each ($phpArray))
{
echo 'jsArray['.$key.'] = "'.$value.'"'."\n";
}
echo '//-->'."\n";
echo '</script>'."\n";
?>