javascript string to bytes

function stringToBytes (str) {
var ch, st, re = [];
for (var i = 0; i < str.length; i++ ) {
ch = str.charCodeAt(i);
st = [];
do {
st.push( ch & 0xFF );
ch = ch >> 8;
} while ( ch );
re = re.concat( st.reverse() );
} // return an array of bytes
return re;
}