Buffer and Binary Data

// Create buffers
const fromString = Buffer.from('Hello, World!');
const fromArray = Buffer.from([72, 101, 108, 108, 111]);
const fromHex = Buffer.from('48656c6c6f', 'hex');
const allocated = Buffer.alloc(16); // zero-filled
const unsafe = Buffer.allocUnsafe(16); // uninitialized (faster)

console.log('From string:', fromString);
console.log('From array:', fromArray.toString());
console.log('From hex:', fromHex.toString());

// Encoding conversions
const text = 'Hello, 🌍!';
const utf8 = Buffer.from(text, 'utf-8');
console.log('\nUTF-8 bytes:', utf8.length);
console.log('As hex:', utf8.toString('hex'));
console.log('As base64:', utf8.toString('base64'));
console.log('As base64url:', utf8.toString('base64url'));

// Base64 encode/decode
function toBase64(str: string): string {
  return Buffer.from(str).toString('base64');
}

function fromBase64(b64: string): string {
  return Buffer.from(b64, 'base64').toString('utf-8');
}

const encoded = toBase64('secret data');
console.log('\nBase64:', encoded);
console.log('Decoded:', fromBase64(encoded));

// Buffer operations
const buf = Buffer.alloc(8);
buf.writeUInt32BE(0x12345678, 0); // Big-endian
buf.writeUInt32LE(0xdeadbeef, 4); // Little-endian
console.log('\nBuffer:', buf.toString('hex'));
console.log('Read BE:', buf.readUInt32BE(0).toString(16));
console.log('Read LE:', buf.readUInt32LE(4).toString(16));

// Float
const floatBuf = Buffer.alloc(4);
floatBuf.writeFloatBE(3.14);
console.log('Float:', floatBuf.readFloatBE().toFixed(2));

// Slice and copy
const original = Buffer.from('Hello, World!');
const slice = original.subarray(0, 5);
console.log('\nSlice:', slice.toString()); // Hello

const copy = Buffer.alloc(5);
original.copy(copy, 0, 7, 12);
console.log('Copy:', copy.toString()); // World

// Concatenate
const combined = Buffer.concat([
  Buffer.from('Hello '),
  Buffer.from('World'),
]);
console.log('Concat:', combined.toString());

// Compare
const a = Buffer.from('abc');
const b = Buffer.from('abc');
const c = Buffer.from('def');
console.log('\nEqual:', a.equals(b)); // true
console.log('Compare:', a.compare(c)); // -1 (a < c)

// Search
const haystack = Buffer.from('Hello World Hello');
console.log('IndexOf:', haystack.indexOf('World')); // 6
console.log('Includes:', haystack.includes('World')); // true

// Iterate
console.log('\nBytes:');
for (const byte of fromString.subarray(0, 5)) {
  console.log(`  ${byte} (${String.fromCharCode(byte)})`);
}