Кирилица

function utf8_decode(utftext) {
var string = "";
var i = 0;
var c = c1 = c2 = 0;

while ( i < utftext.length ) {

c = utftext.charCodeAt(i);

if (c < 128) {
string += String.fromCharCode(c);
i++;
}
else if((c > 191) && (c < 224)) {
c2 = utftext.charCodeAt(i+1);
string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
i += 2;
}
else {
c2 = utftext.charCodeAt(i+1);
c3 = utftext.charCodeAt(i+2);
string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
i += 3;
}

}

return string;
}