Buffers

Code

// Allocate buffers
const buf = Buffer.alloc(8);            // zero-filled
const unsafe = Buffer.allocUnsafe(8);   // uninitialized, faster
const fromStr = Buffer.from("hello", "utf8");
const fromHex = Buffer.from("48656c6c6f", "hex");

// Read and write
buf.writeUInt32BE(0x12345678, 0);
const n = buf.readUInt32BE(0);
console.log(n.toString(16));            // 12345678

// Convert between encodings
const b64 = fromStr.toString("base64");
const decoded = Buffer.from(b64, "base64").toString("utf8");

// Concat and slice
const combined = Buffer.concat([fromStr, Buffer.from("!")]);
const slice = combined.subarray(0, 3);

// Iterate bytes
for (const byte of combined) {
  // byte is 0-255
}

Explanation

Buffer is Node's primary binary data type, a subclass of Uint8Array backed by a chunk of raw memory. alloc initializes memory to zero for safety, while allocUnsafe skips zeroing for speed and is used internally by the runtime. Buffers convert between encodings (utf8, base64, hex) via toString and Buffer.from.

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