This is my toHexString function:
function toHexString(bytes) {
return bytes.map(function (byte) {
return ("00" + (byte & 0xFF).toString(16)).slice(-2)
}).join('')
}
And this is what I have done in Chrome Console:
> var bitmapArray = new Uint8Array(buffer);
undefined
> toHexString(bitmapArray.subarray(0,3))
"2100"
> bitmapArray.subarray(0,3)
[33, 29, 31]
> toHexString([33,29,31])
"211d1f"
It seems that toHexString function cannot work properly. What's the problem?
The map method of typed arrays returns another typed array of the same type. This will cast your strings "21", "1d", "1f" to bytes, by interpreting them as decimal integers - which the latter two are not, so NaN becomes 0 and you end up with the Uint8Array([21, 0, 0]).
To fix this, use a normal Array that can contain strings:
toHexString(Array.from(bitmapArray.subarray(0,3)))
or probably even better
function toHexString(bytes) {
return Array.from(bytes, byte =>
("00" + (byte & 0xFF).toString(16)).slice(-2)
).join('');
}
Array.from. Neither does Safari.
Array.from, but I doubt older browsers would support typed arrays anyway (and certainly not typed arrays with a map method).