How to convert a hexadecimal string to Uint8Array

问题:

I want to convert a hexadecimal string like bada55 into a Uint8Array and back again.

回答1:

Vanilla JS:

const fromHexString = hexString =>
  new Uint8Array(hexString.match(/.{1,2}/g).map(byte => parseInt(byte, 16)));

const toHexString = bytes =>
  bytes.reduce((str, byte) => str + byte.toString(16).padStart(2, '0'), '');

console.log(toHexString(new Uint8Array([0, 1, 2, 42, 100, 101, 102, 255])))
console.log(fromHexString('0001022a646566ff'))

Note: this method always completes. If the length of the hex-encoded buffer is not divisible by 2, the final byte will be parsed as if it were prepended with a 0 (e.g. aaa is interpreted as aa0a).

If the hex is potentially malformed (e.g. user input), check its length and handle the error before calling this method, e.g.:

const missingLetter = 'abc';
if(missingLetter.length % 2 === 0){
  throw new Error(`The string "${missingLetter}" is not divisible by 2.`)
}
fromHexString(missingLetter);

回答2:

Here's a solution in native JavaScript:

var string = 'bada55';
var bytes = new Uint8Array(Math.ceil(string.length / 2));
for (var i = 0; i < bytes.length; i++) bytes[i] = parseInt(string.substr(i * 2, 2), 16);
console.log(bytes);

var convertedBack = '';
for (var i = 0; i < bytes.length; i++) {
  if (bytes[i] < 16) convertedBack += '0';
  convertedBack += bytes[i].toString(16);
}
console.log(convertedBack);

回答3:

Node.js

For JavaScript running on Node you can do this:

const hexString = 'bada55';

const hex = Uint8Array.from(Buffer.from(hexString, 'hex'));

const backToHexString = Buffer.from(hex).toString('hex');

(source: this answer by @Teneff, shared with permission)