PKCE Code Challenge and Code Verifier Generation along with verification process

browser.ts

// browser part
const codeVerifier = crypto.getRandomValues(new Uint8Array(128));

function toBase64(buffer: Uint8Array): string {
  return btoa(String.fromCharCode(...buffer))
    .replace(/=/g, '')
    .replace(/\+/g, '-')
    .replace(/\//g, '_')
}

async function generateCodeChallenge(codeVerifier: Uint8Array): Promise<string> {
  const digest = await crypto.subtle.digest('SHA-256', codeVerifier);
  return toBase64(new Uint8Array(digest));
}

nodejs.ts

// node part
import { createHash } from 'node:crypto';

async function verify(codeVerifier: string, codeChallenge: string) {
  const codeHash = createHash('sha256').update(codeVerifier).digest();
  return codeChallenge === codeHash;

}