function hexToBytes(hex) {

hex = hex.replace(/ /g, ''); // strip spaces

for (var bytes = [], c = 0; c < hex.length; c += 2)

bytes.push(parseInt(hex.substr(c, 2), 16));

return new Uint8Array(bytes);

}

var str = "486579";

var byteArray = hexToBytes(str); // returns Uint8Array(4) [222, 173, 190, 239]

var decoded = new TextDecoder("utf-8").decode(byteArray); // returns "Hey"