Detect text encoding in php

gistfile1.js

public function findEncoding($str) {
    $tab = array("UTF-8", "ASCII", "ISO-8859-1");
    foreach ($tab as $i) {
        foreach ($tab as $j) {
            $chain .= " [iconv('$i','$j','$str'): " . iconv($i, $j, "$str") . "] ";
        }
    }
    return $chain;
}